The Linux SCSI programming HOWTO Heiko Eissfeldt heiko@colossus.escape.de v1.3, 14 April 1995 This document deals with programming the Linux generic SCSI interface. 1. Introduction This document is a guide to the installation and programming of the Linux generic SCSI interface. It covers kernel prerequisites, device mappings, and basic interaction with devices. Some simple C programming examples are included. General knowledge of the SCSI command set is required; for more information on the SCSI standard and related information, see the appendix to this document. 2. What Is The Generic SCSI Interface? The generic SCSI interface has been implemented to provide general SCSI access to (possibly exotic) pieces of SCSI hardware. It was developed by Lawrence Foard ( entropy@world.std.com) and sponsored by Killy Corporation (see the comments in drivers/scsi/sg.h). The interface makes special device handling possible from user level applications (i.e. outside the kernel). Thus, kernel driver development, which is more risky and difficult to debug, is not necessary. However, if you don't program the driver properly it is possible to hang the SCSI bus, the driver, or the kernel. Therefore, it is important to properly program the generic driver and to first back up all files to avoid losing data. Another useful thing to do before running your programs is to issue a sync command to ensure that any buffers are flushed to disk, minimizing data loss if the system hangs. Another advantage of the generic driver is that as long as the interface itself does not change, all applications are independent of new kernel development. In comparison, other low-level kernel drivers have to be synchronized with other internal kernel changes. Typically, the generic driver is used to communicate with new SCSI hardware devices that require special user applications to be written to take advantage of their features (e.g. scanners, printers, CD-ROM jukeboxes). The generic interface allows these to be written quickly. 3. What Are The Requirements To Use It? 3.1. Kernel Configuration You must have a supported SCSI controller, obviously. Furthermore, your kernel must have controller support as well as generic support compiled in. Configuring the Linux kernel (via make config under /usr/src/linux) typically looks like the following: ... * * SCSI support * SCSI support? (CONFIG_SCSI) [n] y * * SCSI support type (disk, tape, CDrom) * ... Scsi generic support (CONFIG_CHR_DEV_SG) [n] y * * SCSI low-level drivers * ... If available, modules can of course be build instead. 3.2. Device Files The generic SCSI driver uses its own device files, separate from those used by the other SCSI device drivers. They can be generated using the MAKEDEV script, typically found in the /dev directory. Running MAKEDEV sg produces these files: crw------- 1 root system 21, 0 Aug 20 20:09 /dev/sga crw------- 1 root system 21, 1 Aug 20 20:09 /dev/sgb crw------- 1 root system 21, 2 Aug 20 20:09 /dev/sgc crw------- 1 root system 21, 3 Aug 20 20:09 /dev/sgd crw------- 1 root system 21, 4 Aug 20 20:09 /dev/sge crw------- 1 root system 21, 5 Aug 20 20:09 /dev/sgf crw------- 1 root system 21, 6 Aug 20 20:09 /dev/sgg crw------- 1 root system 21, 7 Aug 20 20:09 /dev/sgh | | major, minor device numbers Note that these are character devices for raw access. On some systems these devices may be called /dev/{sg0,sg1,...}, depending on your installation, so adjust the following examples accordingly. 3.3. Device Mapping These device files are dynamically mapped to SCSI id/LUNs on your SCSI bus (LUN = logical unit). The mapping allocates devices consecutively for each LUN of each device on each SCSI bus found at time of the SCSI scan, beginning at the lower LUNs/ids/buses. It starts with the first SCSI controller and continues without interruption with all following controllers. This is currently done in the initialisation of the SCSI driver. For example, assuming you had three SCSI devices hooked up with ids 1, 3, and 5 on the first SCSI bus (each having one LUN), then the following mapping would be in effect: /dev/sga -> SCSI id 1 /dev/sgb -> SCSI id 3 /dev/sgc -> SCSI id 5 If you now add a new device with id 4, then the mapping (after the next rescan) will be: /dev/sga -> SCSI id 1 /dev/sgb -> SCSI id 3 /dev/sgc -> SCSI id 4 /dev/sgd -> SCSI id 5 Notice the change for id 5 -- the corresponding device is no longer mapped to /dev/sgc but is now /dev/sgd. 3.3.1. Rescanning the devices To force a rescan, a modularized driver could be deleted and reinserted. At initialisation time it will rescan the buses. But in order to be able to delete the driver, none of its devices may be used at that time. When adding more devices to the scsi buses keep in mind there are limited spare entries for new devices. The memory had been allocated at boot time and has room for 2 more disks, 2 more CDROMs, 2 more tapes and 2 more generic devices. Scanning the scsi buses on your own is not recommended. There are too many (buggy) devices that may hang the scsi bus, when being addressed with a LUN value that is not 0. The kernel manages a private table with known flawed devices, where it scans with LUN 0 only. 4. Programmers Guide The following sections are for programmers who want to use the generic SCSI interface in their own applications. An example will be given showing how to access a SCSI device with the INQUIRY and the TESTUNITREADY commands. When using these code examples, note the following: o the generic SCSI interface was extended in kernel version 1.1.68; the examples require at least this version. But please avoid kernel version 1.1.77 up to 1.1.89 since they had a broken generic scsi interface. o the constant DEVICE in the header section describing the accessed device should be set according to your available devices (see section ``''. 5. Overview Of Device Programming The header file drivers/scsi/sg.h under the Linux source tree contains a description of the interface (this is based on kernel version 1.1.68): struct sg_header { int pack_len; /* length of incoming packet <4096 (including header) */ int reply_len; /* maximum length <4096 of expected reply */ int pack_id; /* id number of packet */ int result; /* 0==ok, otherwise refer to errno codes */ unsigned int twelve_byte:1; /* Force 12 byte command length for group 6 & 7 commands */ unsigned int other_flags:31; /* for future use */ unsigned char sense_buffer[16]; /* used only by reads */ /* command follows then data for command */ }; This structure describes how a SCSI command is to be processed and has room to hold the results of the execution of the command. The individual structure components will be discussed later in section ``''. The general way of exchanging data with the generic driver is as follows: to send a command to an opened generic device, write() a block containing these three parts to it: struct sg_header SCSI command output data To obtain the result of a command, read() a block with this similar block structure: struct sg_header input data NOTE: Up to recent kernel versions, it is necessary to block the SIGINT signal between the write() and the corresponding read() call (i.e. via sigprocmask()). A return after the write() part without any read() to fetch the results will block on subsequent accesses. This signal blocking has not yet been included in the example code. This is a general overview of the process. The following sections describe each of the steps in more detail. 6. Opening The Device A generic device has to be opened for read and write access: int fd = open (device_name, O_RDWR); (This is the case even for a read-only hardware device such as a cdrom drive). We have to perform a write to send the command and a read to get back any results. In the case of an error the return code is negative (see section ``'' for a complete list). 7. The Header Structure The header structure struct sg_header serves as a controlling layer between the application and the kernel driver. We now discuss its components in detail. int pack_len defines the size of the block written to the driver. This is defined from the application side. int reply_len defines the size of the block to be accepted at reply. This is defined from the application side. int pack_id This field helps to assign replies to requests. The application can supply a unique id for each request. Suppose you have written several commands (say 4) to one device. They may work in parallel, one being the fastest. When getting replies via 4 reads, the replies do not have to have the order of the requests. To identify the correct reply for a given request one can use the pack_id field. Typically its value is incremented after each request (and wraps eventually). int result the result code of a read or write call. This is defined from the generic driver (kernel) side. These codes are defined in errno.h (0 meaning no error). unsigned int twelve_byte:1 This field is necessary only when using non-standard vendor specific commands (in the range 0xc0 - 0xff). When these commands have a command length of 12 bytes instead of 10, this field has to be set to one before the write call. Other command lengths are not supported. This is defined from the application side. unsigned char sense_buffer16 This buffer is set after a command is completed (after a read() call) and contains the SCSI sense code. Some command results have to be read from here (e.g. for TESTUNITREADY). Usually it contains just zero bytes. The value in this field is set by the generic driver (kernel) side. The following example function interfaces directly with the generic kernel driver. It defines the header structure, sends the command via write, gets the result via read and does some (limited) error checking. The sense buffer data is available in the output buffer (unless a NULL pointer has been given, in which case it's in the input buffer). We will use it in the examples which follow. Note: Set the value of DEVICE to your device descriptor. /* Example program to demonstrate the generic SCSI interface */ #include #include #include #include #include #include #define DEVICE "/dev/sgc" #define SCSI_OFF sizeof(struct sg_header) static unsigned char cmd[SCSI_OFF + 18]; /* SCSI command buffer */ int fd; /* SCSI device/file descriptor */ /* process a complete SCSI cmd. Use the generic SCSI interface. */ static int handle_SCSI_cmd(unsigned cmd_len, /* command length */ unsigned in_size, /* input data size */ unsigned char *i_buff, /* input buffer */ unsigned out_size, /* output data size */ unsigned char *o_buff /* output buffer */ ) { int status = 0; struct sg_header *sg_hd; /* safety checks */ if (!cmd_len) return -1; /* need a cmd_len != 0 */ if (!i_buff) return -1; /* need an input buffer != NULL */ #ifdef SG_BIG_BUFF if (SCSI_OFF + cmd_len + in_size > SG_BIG_BUFF) return -1; if (SCSI_OFF + out_size > SG_BIG_BUFF) return -1; #else if (SCSI_OFF + cmd_len + in_size > 4096) return -1; if (SCSI_OFF + out_size > 4096) return -1; #endif if (!o_buff) out_size = 0; /* no output buffer, no output size */ /* generic SCSI device header construction */ sg_hd = (struct sg_header *) i_buff; sg_hd->pack_len = SCSI_OFF + cmd_len + in_size; sg_hd->reply_len = SCSI_OFF + out_size; sg_hd->twelve_byte = cmd_len == 12; #if 0 sg_hd->pack_id; /* not used */ sg_hd->other_flags; /* not used */ #endif /* send command */ status = write( fd, i_buff, SCSI_OFF + cmd_len + in_size ); if ( status < 0 || status != SCSI_OFF + cmd_len + in_size || sg_hd->result ) { /* some error happened */ fprintf( stderr, "write(generic) result = 0x%x cmd = 0x%x\n", sg_hd->result, i_buff[SCSI_OFF] ); perror(""); return status; } if (!o_buff) o_buff = i_buff; /* buffer pointer check */ /* retrieve result */ status = read( fd, o_buff, SCSI_OFF + out_size); if ( status < 0 || status != SCSI_OFF + out_size || sg_hd->result ) { /* some error happened */ fprintf( stderr, "read(generic) status = 0x%x, result = 0x%x, " "cmd = 0x%x\n", status, sg_hd->result, o_buff[SCSI_OFF] ); fprintf( stderr, "read(generic) sense " "%x %x %x %x %x %x %x %x %x %x %x %x %x %x %x %x\n", sg_hd->sense_buffer[0], sg_hd->sense_buffer[1], sg_hd->sense_buffer[2], sg_hd->sense_buffer[3], sg_hd->sense_buffer[4], sg_hd->sense_buffer[5], sg_hd->sense_buffer[6], sg_hd->sense_buffer[7], sg_hd->sense_buffer[8], sg_hd->sense_buffer[9], sg_hd->sense_buffer[10], sg_hd->sense_buffer[11], sg_hd->sense_buffer[12], sg_hd->sense_buffer[13], sg_hd->sense_buffer[14], sg_hd->sense_buffer[15]); } /* Look if we got what we expected to get */ if (status == SCSI_OFF + out_size) status = 0; /* got them all */ return status; /* 0 means no error */ } While this may look somewhat complex at first appearance, most of the code is for error checking and reporting (which is useful even after the code is working). Handle_SCSI_cmd has a generalized form for all SCSI commands types, falling into each of these categories: Data Mode | Example Command =============================================== neither input nor output data | test unit ready no input data, output data | inquiry, read input data, no output data | mode select, write input data, output data | mode sense 8. Inquiry Command Example One of the most basic SCSI commands is the INQUIRY command, used to identify the type and make of the device. Here is the definition from the SCSI-2 specification (for details refer to the SCSI-2 standard). Table 44: INQUIRY Command +=====-========-========-========-========-========-========-========-========+ | Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |Byte | | | | | | | | | |=====+=======================================================================| | 0 | Operation Code (12h) | |-----+-----------------------------------------------------------------------| | 1 | Logical Unit Number | Reserved | EVPD | |-----+-----------------------------------------------------------------------| | 2 | Page Code | |-----+-----------------------------------------------------------------------| | 3 | Reserved | |-----+-----------------------------------------------------------------------| | 4 | Allocation Length | |-----+-----------------------------------------------------------------------| | 5 | Control | +=============================================================================+ The output data are as follows: Table 45: Standard INQUIRY Data Format +=====-========-========-========-========-========-========-========-========+ | Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |Byte | | | | | | | | | |=====+==========================+============================================| | 0 | Peripheral Qualifier | Peripheral Device Type | |-----+-----------------------------------------------------------------------| | 1 | RMB | Device-Type Modifier | |-----+-----------------------------------------------------------------------| | 2 | ISO Version | ECMA Version | ANSI-Approved Version | |-----+-----------------+-----------------------------------------------------| | 3 | AENC | TrmIOP | Reserved | Response Data Format | |-----+-----------------------------------------------------------------------| | 4 | Additional Length (n-4) | |-----+-----------------------------------------------------------------------| | 5 | Reserved | |-----+-----------------------------------------------------------------------| | 6 | Reserved | |-----+-----------------------------------------------------------------------| | 7 | RelAdr | WBus32 | WBus16 | Sync | Linked |Reserved| CmdQue | SftRe | |-----+-----------------------------------------------------------------------| | 8 | (MSB) | |- - -+--- Vendor Identification ---| | 15 | (LSB) | |-----+-----------------------------------------------------------------------| | 16 | (MSB) | |- - -+--- Product Identification ---| | 31 | (LSB) | |-----+-----------------------------------------------------------------------| | 32 | (MSB) | |- - -+--- Product Revision Level ---| | 35 | (LSB) | |-----+-----------------------------------------------------------------------| | 36 | | |- - -+--- Vendor Specific ---| | 55 | | |-----+-----------------------------------------------------------------------| | 56 | | |- - -+--- Reserved ---| | 95 | | |=====+=======================================================================| | | Vendor-Specific Parameters | |=====+=======================================================================| | 96 | | |- - -+--- Vendor Specific ---| | n | | +=============================================================================+ The next example uses the low-level function handle_SCSI_cmd to perform the Inquiry SCSI command. We first append the command block to the generic header, then call handle_SCSI_cmd. Note that the output buffer size argument for the handle_SCSI_cmd call excludes the generic header size. After command completion the output buffer contains the requested data, unless an error occurred. #define INQUIRY_CMD 0x12 #define INQUIRY_CMDLEN 6 #define INQUIRY_REPLY_LEN 96 #define INQUIRY_VENDOR 8 /* Offset in reply data to vendor name */ /* request vendor brand and model */ static unsigned char *Inquiry ( void ) { unsigned char Inqbuffer[ SCSI_OFF + INQUIRY_REPLY_LEN ]; unsigned char cmdblk [ INQUIRY_CMDLEN ] = { INQUIRY_CMD, /* command */ 0, /* lun/reserved */ 0, /* page code */ 0, /* reserved */ INQUIRY_REPLY_LEN, /* allocation length */ 0 };/* reserved/flag/link */ memcpy( cmd + SCSI_OFF, cmdblk, sizeof(cmdblk) ); if (handle_SCSI_cmd(sizeof(cmdblk), 0, cmd, sizeof(Inqbuffer) - SCSI_OFF, Inqbuffer )) { fprintf( stderr, "Inquiry failed\n" ); exit(2); } return (Inqbuffer + SCSI_OFF); } The example above follows this structure. The Inquiry function copies its command block behind the generic header (given by SCSI_OFF). Input data is not present for this command. Handle_SCSI_cmd will define the header structure. We can now implement the function main to complete this working example program. void main( void ) { fd = open(DEVICE, O_RDWR); if (fd < 0) { fprintf( stderr, "Need read/write permissions for "DEVICE".\n" ); exit(1); } /* print the result of Inquiry */ printf( "%s\n", Inquiry() + INQUIRY_VENDOR ); } We first open the device, check for errors, and then call the higher level subroutine. Then we print the results in human readable format including the vendor, product, and revision. 9. The Sense Buffer Commands with no output data can give status information via the sense buffer (which is part of the header structure). Sense data is available when the previous command has terminated with a CHECK CONDITION status. In this case the kernel automatically retrieves the sense data via a REQUEST SENSE command. Its structure is: +=====-========-========-========-========-========-========-========-========+ | Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |Byte | | | | | | | | | |=====+========+==============================================================| | 0 | Valid | Error Code (70h or 71h) | |-----+-----------------------------------------------------------------------| | 1 | Segment Number | |-----+-----------------------------------------------------------------------| | 2 |Filemark| EOM | ILI |Reserved| Sense Key | |-----+-----------------------------------------------------------------------| | 3 | (MSB) | |- - -+--- Information ---| | 6 | (LSB) | |-----+-----------------------------------------------------------------------| | 7 | Additional Sense Length (n-7) | |-----+-----------------------------------------------------------------------| | 8 | (MSB) | |- - -+--- Command-Specific Information ---| | 11 | (LSB) | |-----+-----------------------------------------------------------------------| | 12 | Additional Sense Code | |-----+-----------------------------------------------------------------------| | 13 | Additional Sense Code Qualifier | |-----+-----------------------------------------------------------------------| | 14 | Field Replaceable Unit Code | |-----+-----------------------------------------------------------------------| | 15 | SKSV | | |- - -+------------ Sense-Key Specific ---| | 17 | | |-----+-----------------------------------------------------------------------| | 18 | | |- - -+--- Additional Sense Bytes ---| | n | | +=============================================================================+ Note: The most useful fields are Sense Key (see section ``''), Additional Sense Code and Additional Sense Code Qualifier (see section ``''). The latter two are combined. 10. Example Using Sense Buffer Here we will use the TEST UNIT READY command to check whether media is loaded into our device. The header declarations and function handle_SCSI_cmd from the inquiry example will be needed as well. Table 73: TEST UNIT READY Command +=====-========-========-========-========-========-========-========-========+ | Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |Byte | | | | | | | | | |=====+=======================================================================| | 0 | Operation Code (00h) | |-----+-----------------------------------------------------------------------| | 1 | Logical Unit Number | Reserved | |-----+-----------------------------------------------------------------------| | 2 | Reserved | |-----+-----------------------------------------------------------------------| | 3 | Reserved | |-----+-----------------------------------------------------------------------| | 4 | Reserved | |-----+-----------------------------------------------------------------------| | 5 | Control | +=============================================================================+ Here is the function which implements it: #define TESTUNITREADY_CMD 0 #define TESTUNITREADY_CMDLEN 6 #define ADD_SENSECODE 12 #define ADD_SC_QUALIFIER 13 #define NO_MEDIA_SC 0x3a #define NO_MEDIA_SCQ 0x00 int TestForMedium ( void ) { /* request READY status */ static unsigned char cmdblk [TESTUNITREADY_CMDLEN] = { TESTUNITREADY_CMD, /* command */ 0, /* reserved */ 0, /* reserved */ 0, /* reserved */ 0, /* reserved */ 0};/* control */ memcpy( cmd + SCSI_OFF, cmdblk, sizeof(cmdblk) ); if (handle_SCSI_cmd(sizeof(cmdblk), 0, cmd, 0, NULL)) { fprintf (stderr, "Test unit ready failed\n"); exit(2); } return *(((struct sg_header*)cmd)->sense_buffer +ADD_SENSECODE) != NO_MEDIA_SC || *(((struct sg_header*)cmd)->sense_buffer +ADD_SC_QUALIFIER) != NO_MEDIA_SCQ; } Combined with this main function we can do the check. void main( void ) { fd = open(DEVICE, O_RDWR); if (fd < 0) { fprintf( stderr, "Need read/write permissions for "DEVICE".\n" ); exit(1); } /* look if medium is loaded */ if (!TestForMedium()) { printf("device is unloaded\n"); } else { printf("device is loaded\n"); } } The file generic_demo.c from the appendix contains both examples. 11. Ioctl Functions There are two ioctl functions available: o ioctl(fd, SG_SET_TIMEOUT, &Timeout); sets the timeout value to Timeout * 10 milliseconds. Timeout has to be declared as int. o ioctl(fd, SG_GET_TIMEOUT, &Timeout); gets the current timeout value. Timeout has to be declared as int. 12. Driver Defaults 12.1. Transfer Lengths Currently (at least up to kernel version 1.1.68) input and output sizes have to be less than or equal than 4096 bytes unless the kernel has been compiled with SG_BIG_BUFF defined, if which case it is limited to SG_BIG_BUFF (e.g. 32768) bytes. These sizes include the generic header as well as the command block on input. 12.2. Timeout And Retry Values The default timeout value is set to one minute (Timeout = 6000). It can be changed through an ioctl call (see section ``''). The default number of retries is one. 13. Obtaining The Scsi Specifications There are standards entitled SCSI-1 and SCSI-2 (and possibly soon SCSI-3). The standards are mostly upward compatible. The SCSI-1 standard is (in the author's opinion) mostly obsolete, and SCSI-2 is the most widely used. SCSI-3 is very new and very expensive. These standardized command sets specify mandatory and optional commands for SCSI manufacturers and should be preferred over the vendor specific command extensions which are not standardized and for which programming information is seldom available. Of course sometimes there is no alternative to these extensions. Electronic copies are available via anonymous ftp from: o ftp.cs.tulane.edu:pub/scsi o ncrinfo.ncr.com:/pub/standards o ftp.cs.uni-sb.de:/pub/misc/doc/scsi (I got my SCSI specification from the Yggdrasil Linux CD-ROM in the directory /usr/doc/scsi-2 and /usr/doc/scsi-1). The SCSI FAQ also lists the following sources of printed information: The SCSI specification: Available from: Global Engineering Documents 15 Inverness Way East Englewood Co 80112-5704 (800) 854-7179 SCSI-1: X3.131-1986 SCSI-2: X3.131-199x SCSI-3 X3T9.2/91-010R4 Working Draft (Global Engineering Documentation in Irvine, CA (714)261-1455??) SCSI-1: Doc \# X3.131-1986 from ANSI, 1430 Broadway, NY, NY 10018 IN-DEPTH EXPLORATION OF SCSI can be obtained from Solution Technology, Attn: SCSI Publications, POB 104, Boulder Creek, CA 95006, (408)338-4285, FAX (408)338-4374 THE SCSI ENCYLOPEDIA and the SCSI BENCH REFERENCE can be obtained from ENDL Publishing, 14426 Black Walnut Ct., Saratoga, CA 95090, (408)867-6642, FAX (408)867-2115 SCSI: UNDERSTANDING THE SMALL COMPUTER SYSTEM INTERFACE was published by Prentice-Hall, ISBN 0-13-796855-8 14. Related Information Sources The Linux SCSI-HOWTO by Drew Eckhardt covers all supported SCSI controllers as well as device specific questions. A lot of troubleshooting hints are given. It is available from sunsite.unc.edu in /pub/Linux/docs/LDP and its mirror sites. General questions about SCSI are answered in the SCSI-FAQ from the newsgroup Comp.Periphs.Scsi (available on tsx-11 in pub/linux/ALPHA/scsi and mirror sites). There is a mailing list for bug reports and questions regarding SCSI development under Linux. To join, send email to majordomo@vger.rutgers.edu with the line subscribe linux-scsi in the body of the message. Messages should be posted to linux- scsi@vger.rutgers.edu. Help text can be requested by sending the message line "help" to majordomo@vger.rutgers.edu. There is another mailing list server at niksula.hut.fi, but it has been very busy (read too busy) lately. 15. Other SCSI Access Interfaces There are some other similar interfaces in use in the un*x world, but not available for Linux: 1. CAM (Common Access Method) developed by Future Domain and other SCSI vendors. This was a response to the ASPI interface. Linux has some support for a SCSI CAM system (mainly for booting from hard disk). CAM even supports target mode, so one could disguise ones computer as a peripheral hardware device (e.g. for a small SCSI net). 2. ASPI (Advanced SCSI Programming Interface) developed by Adaptec. This is the de facto standard for MS-DOS machines. There are other application interfaces from SCO(TM), NeXT(TM), Silicon Graphics(TM) and SUN(TM) as well. 16. Final Comments The generic SCSI interface bridges the gap between user applications and specific devices. But rather than bloating a lot of programs with similar sets of low-level functions, it would be more desirable to have a shared library with a generalized set of low-level functions for a particular purpose. The main goal should be to have independent layers of interfaces. A good design would separate an application into low-level and hardware independent routines. The low-level routines could be put into a shared library and made available for all applications. Here, standardized interfaces should be followed as much as possible before making new ones. By now you should know more than I do about the Linux generic SCSI interface. So you can start developing powerful applications for the benefit of the global Linux community now... 17. Acknowledgments Special thanks go to Jeff Tranter for proofreading and enhancing the text considerably as well as to Carlos Puchol for useful comments. Drew Eckhardt's and Eric Youngdale's help on my first (dumb) questions about the use of this interface has been appreciated. R. Appendix S. Error handling The functions open, ioctl, write and read can report errors. In this case their return value is -1 and the global variable errno is set to the error number (negative). The errno values are defined in /usr/include/errno.h. Possible negative values are: Function | Error | Description =========|==============|============================================= open | -ENXIO | not a valid device | -EACCES | access mode is not read/write (O_RDWR) | -EBUSY | device was requested for nonblocking access, | | but is busy now. | -ERESTARTSYS | this indicates an internal error. Try to | | make it reproducible and inform the SCSI | | channel (for details on bug reporting | | see Drew Eckhardts SCSI-HOWTO). ioctl | -ENXIO | not a valid device read | -EWOULDBLOCK | the device would block. Try again later. write | -EIO | the length is too small (smaller than the | | generic header struct). Caution: Currently | | there is no overlength checking. | -EWOULDBLOCK | the device would block. Try again later. | -ERESTARTSYS | this indicates an internal error. Try to | | make it reproducible and inform the SCSI | | channel (for details on bug reporting | | see Drew Eckhardts SCSI-HOWTO). | -ENOMEM | memory required for this request could not be | | allocated. Try later again unless you | | exceeded the maximum transfer size (see above) For read/write positive return values indicate as usual the amount of bytes that have been successfully transferred. This should equal the amount you requested. S.1. Error status decoding Furthermore a detailed reporting is done via the kernels hd_status and the devices reports in the sense_buffer (see section ``'') from the header structure. The meaning of hd_status can be found in drivers/scsi/scsi.h: This unsigned int is composed out of different parts: lsb | ... | ... | msb =======|===========|===========|============ status | sense key | host code | driver byte These macros from drivers/scsi/scsi.h can be used to separate the fields: Macro | Description ====================|================================================ status_byte(result) | The SCSI device status. See above msg_byte(result) | The devices sense key. See above host_byte(result) | The host code from the kernel driver. See above driver_byte(result) | The first byte from the device S.2. Status codes The following status codes from the SCSI device (defined in drivers/scsi/scsi.h) should be used with the macro status_byte (see section ``''): Value | Symbol ======|===================== 0x00 | GOOD 0x01 | CHECK_CONDITION 0x02 | CONDITION_GOOD 0x04 | BUSY 0x08 | INTERMEDIATE_GOOD 0x0a | INTERMEDIATE_C_GOOD 0x0c | RESERVATION_CONFLICT Note that these symbol values have been shifted right once. From the SCSI-2 specification: Table 27: Status Byte Code +=================================-==============================+ | Bits of Status Byte | Status | | 7 6 5 4 3 2 1 0 | | |---------------------------------+------------------------------| | R R 0 0 0 0 0 R | GOOD | | R R 0 0 0 0 1 R | CHECK CONDITION | | R R 0 0 0 1 0 R | CONDITION MET | | R R 0 0 1 0 0 R | BUSY | | R R 0 1 0 0 0 R | INTERMEDIATE | | R R 0 1 0 1 0 R | INTERMEDIATE-CONDITION MET | | R R 0 1 1 0 0 R | RESERVATION CONFLICT | | R R 1 0 0 0 1 R | COMMAND TERMINATED | | R R 1 0 1 0 0 R | QUEUE FULL | | | | | All Other Codes | Reserved | |----------------------------------------------------------------| | Key: R = Reserved bit | +================================================================+ A definition of the status byte codes is given below. GOOD. This status indicates that the target has successfully completed the command. CHECK CONDITION. This status indicates that a contingent allegiance condition has occurred (see 6.6). CONDITION MET. This status or INTERMEDIATE-CONDITION MET is returned whenever the requested operation is satisfied (see the SEARCH DATA and PRE-FETCH commands). BUSY. This status indicates that the target is busy. This status shall be returned whenever a target is unable to accept a command from an otherwise acceptable initiator (i.e., no reservation conflicts). The recommended initiator recovery action is to issue the command again at a later time. INTERMEDIATE. This status or INTERMEDIATE-CONDITION MET shall be returned for every successfully completed command in a series of linked commands (except the last command), unless the command is terminated with CHECK CONDITION, RESERVATION CONFLICT, or COMMAND TERMINATED status. If INTERMEDIATE or INTERMEDIATE-CONDITION MET status is not returned, the series of linked commands is terminated and the I/O process is ended. INTERMEDIATE-CONDITION MET. This status is the combination of the CONDITION MET and INTERMEDIATE statuses. RESERVATION CONFLICT. This status shall be returned whenever an initiator attempts to access a logical unit or an extent within a logical unit that is reserved with a conflicting reservation type for another SCSI device (see the RESERVE and RESERVE UNIT commands). The recommended initiator recovery action is to issue the command again at a later time. COMMAND TERMINATED. This status shall be returned whenever the target terminates the current I/O process after receiving a TERMINATE I/O PROCESS message (see 5.6.22). This status also indicates that a contingent allegiance condition has occurred (see 6.6). QUEUE FULL. This status shall be implemented if tagged queuing is implemented. This status is returned when a SIMPLE QUEUE TAG, ORDERED QUEUE TAG, or HEAD OF QUEUE TAG message is received and the command queue is full. The I/O process is not placed in the command queue. S.3. SCSI Sense Keys The sense key from the result should be retrieved with the macro msg_byte (see section ``''). These kernel symbols (from drivers/scsi/scsi.h) are predefined: Value | Symbol ======|================ 0x00 | NO_SENSE 0x01 | RECOVERED_ERROR 0x02 | NOT_READY 0x03 | MEDIUM_ERROR 0x04 | HARDWARE_ERROR 0x05 | ILLEGAL_REQUEST 0x06 | UNIT_ATTENTION 0x07 | DATA_PROTECT 0x08 | BLANK_CHECK 0x0a | COPY_ABORTED 0x0b | ABORTED_COMMAND 0x0d | VOLUME_OVERFLOW 0x0e | MISCOMPARE A verbatim list from the SCSI-2 doc follows (from section 7.2.14.3): Table 69: Sense Key (0h-7h) Descriptions +========-====================================================================+ | Sense | Description | | Key | | |--------+--------------------------------------------------------------------| | 0h | NO SENSE. Indicates that there is no specific sense key | | | information to be reported for the designated logical unit. This | | | would be the case for a successful command or a command that | | | received CHECK CONDITION or COMMAND TERMINATED status because one | | | of the filemark, EOM, or ILI bits is set to one. | |--------+--------------------------------------------------------------------| | 1h | RECOVERED ERROR. Indicates that the last command completed | | | successfully with some recovery action performed by the target. | | | Details may be determinable by examining the additional sense | | | bytes and the information field. When multiple recovered errors | | | occur during one command, the choice of which error to report | | | (first, last, most severe, etc.) is device specific. | |--------+--------------------------------------------------------------------| | 2h | NOT READY. Indicates that the logical unit addressed cannot be | | | accessed. Operator intervention may be required to correct this | | | condition. | |--------+--------------------------------------------------------------------| | 3h | MEDIUM ERROR. Indicates that the command terminated with a non- | | | recovered error condition that was probably caused by a flaw in | | | the medium or an error in the recorded data. This sense key may | | | also be returned if the target is unable to distinguish between a | | | flaw in the medium and a specific hardware failure (sense key 4h).| |--------+--------------------------------------------------------------------| | 4h | HARDWARE ERROR. Indicates that the target detected a non- | | | recoverable hardware failure (for example, controller failure, | | | device failure, parity error, etc.) while performing the command | | | or during a self test. | |--------+--------------------------------------------------------------------| | 5h | ILLEGAL REQUEST. Indicates that there was an illegal parameter in| | | the command descriptor block or in the additional parameters | | | supplied as data for some commands (FORMAT UNIT, SEARCH DATA, | | | etc.). If the target detects an invalid parameter in the command | | | descriptor block, then it shall terminate the command without | | | altering the medium. If the target detects an invalid parameter | | | in the additional parameters supplied as data, then the target may| | | have already altered the medium. This sense key may also indicate| | | that an invalid IDENTIFY message was received (5.6.7). | |--------+--------------------------------------------------------------------| | 6h | UNIT ATTENTION. Indicates that the removable medium may have been| | | changed or the target has been reset. See 6.9 for more detailed | | | information about the unit attention condition. | |--------+--------------------------------------------------------------------| | 7h | DATA PROTECT. Indicates that a command that reads or writes the | | | medium was attempted on a block that is protected from this | | | operation. The read or write operation is not performed. | +=============================================================================+ Table 70: Sense Key (8h-Fh) Descriptions +========-====================================================================+ | Sense | Description | | Key | | |--------+--------------------------------------------------------------------| | 8h | BLANK CHECK. Indicates that a write-once device or a sequential- | | | access device encountered blank medium or format-defined end-of- | | | data indication while reading or a write-once device encountered a| | | non-blank medium while writing. | |--------+--------------------------------------------------------------------| | 9h | Vendor Specific. This sense key is available for reporting vendor| | | specific conditions. | |--------+--------------------------------------------------------------------| | Ah | COPY ABORTED. Indicates a COPY, COMPARE, or COPY AND VERIFY | | | command was aborted due to an error condition on the source | | | device, the destination device, or both. (See 7.2.3.2 for | | | additional information about this sense key.) | |--------+--------------------------------------------------------------------| | Bh | ABORTED COMMAND. Indicates that the target aborted the command. | | | The initiator may be able to recover by trying the command again. | |--------+--------------------------------------------------------------------| | Ch | EQUAL. Indicates a SEARCH DATA command has satisfied an equal | | | comparison. | |--------+--------------------------------------------------------------------| | Dh | VOLUME OVERFLOW. Indicates that a buffered peripheral device has | | | reached the end-of-partition and data may remain in the buffer | | | that has not been written to the medium. A RECOVER BUFFERED DATA | | | command(s) may be issued to read the unwritten data from the | | | buffer. | |--------+--------------------------------------------------------------------| | Eh | MISCOMPARE. Indicates that the source data did not match the data| | | read from the medium. | |--------+--------------------------------------------------------------------| | Fh | RESERVED. | +=============================================================================+ S.4. Hostcodes The following host codes are defined in drivers/scsi/scsi.h. They are set by the kernel driver and should be used with the macro host_byte (see section ``''): Value | Symbol | Description ======|================|======================================== 0x00 | DID_OK | No error 0x01 | DID_NO_CONNECT | Couldn't connect before timeout period 0x02 | DID_BUS_BUSY | BUS stayed busy through time out period 0x03 | DID_TIME_OUT | TIMED OUT for other reason 0x04 | DID_BAD_TARGET | BAD target 0x05 | DID_ABORT | Told to abort for some other reason 0x06 | DID_PARITY | Parity error 0x07 | DID_ERROR | internal error 0x08 | DID_RESET | Reset by somebody 0x09 | DID_BAD_INTR | Got an interrupt we weren't expecting T. Additional sense codes and additional sense code qualifiers From the SCSI-2 specification I include two tables. The first is in lexical, the second in numerical order. T.1. ASC and ASCQ in lexical order The following table list gives a list of descriptions and device types they apply to. +=============================================================================+ | D - DIRECT ACCESS DEVICE | | .T - SEQUENTIAL ACCESS DEVICE | | . L - PRINTER DEVICE | | . P - PROCESSOR DEVICE | | . .W - WRITE ONCE READ MULTIPLE DEVICE | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 13h 00h D W O ADDRESS MARK NOT FOUND FOR DATA FIELD | | 12h 00h D W O ADDRESS MARK NOT FOUND FOR ID FIELD | | 00h 11h R AUDIO PLAY OPERATION IN PROGRESS | | 00h 12h R AUDIO PLAY OPERATION PAUSED | | 00h 14h R AUDIO PLAY OPERATION STOPPED DUE TO ERROR | | 00h 13h R AUDIO PLAY OPERATION SUCCESSFULLY COMPLETED | | 00h 04h T S BEGINNING-OF-PARTITION/MEDIUM DETECTED | | 14h 04h T BLOCK SEQUENCE ERROR | | 30h 02h DT WR O CANNOT READ MEDIUM - INCOMPATIBLE FORMAT | | 30h 01h DT WR O CANNOT READ MEDIUM - UNKNOWN FORMAT | | 52h 00h T CARTRIDGE FAULT | | 3Fh 02h DTLPWRSOMC CHANGED OPERATING DEFINITION | | 11h 06h WR O CIRC UNRECOVERED ERROR | | 30h 03h DT CLEANING CARTRIDGE INSTALLED | | 4Ah 00h DTLPWRSOMC COMMAND PHASE ERROR | | 2Ch 00h DTLPWRSOMC COMMAND SEQUENCE ERROR | | 2Fh 00h DTLPWRSOMC COMMANDS CLEARED BY ANOTHER INITIATOR | | 2Bh 00h DTLPWRSO C COPY CANNOT EXECUTE SINCE HOST CANNOT DISCONNECT | | 41h 00h D DATA PATH FAILURE (SHOULD USE 40 NN) | | 4Bh 00h DTLPWRSOMC DATA PHASE ERROR | | 11h 07h W O DATA RESYCHRONIZATION ERROR | | 16h 00h D W O DATA SYNCHRONIZATION MARK ERROR | | 19h 00h D O DEFECT LIST ERROR | | 19h 03h D O DEFECT LIST ERROR IN GROWN LIST | | 19h 02h D O DEFECT LIST ERROR IN PRIMARY LIST | | 19h 01h D O DEFECT LIST NOT AVAILABLE | | 1Ch 00h D O DEFECT LIST NOT FOUND | | 32h 01h D W O DEFECT LIST UPDATE FAILURE | | 40h NNh DTLPWRSOMC DIAGNOSTIC FAILURE ON COMPONENT NN (80H-FFH) | | 63h 00h R END OF USER AREA ENCOUNTERED ON THIS TRACK | | 00h 05h T S END-OF-DATA DETECTED | | 14h 03h T END-OF-DATA NOT FOUND | | 00h 02h T S END-OF-PARTITION/MEDIUM DETECTED | | 51h 00h T O ERASE FAILURE | | 0Ah 00h DTLPWRSOMC ERROR LOG OVERFLOW | | 11h 02h DT W SO ERROR TOO LONG TO CORRECT | | 03h 02h T EXCESSIVE WRITE ERRORS | | 3Bh 07h L FAILED TO SENSE BOTTOM-OF-FORM | | 3Bh 06h L FAILED TO SENSE TOP-OF-FORM | | 00h 01h T FILEMARK DETECTED | | 14h 02h T FILEMARK OR SETMARK NOT FOUND | | 09h 02h WR O FOCUS SERVO FAILURE | | 31h 01h D L O FORMAT COMMAND FAILED | | 58h 00h O GENERATION DOES NOT EXIST | +=============================================================================+ Table 71: (continued) +=============================================================================+ | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 1Ch 02h D O GROWN DEFECT LIST NOT FOUND | | 00h 06h DTLPWRSOMC I/O PROCESS TERMINATED | | 10h 00h D W O ID CRC OR ECC ERROR | | 22h 00h D ILLEGAL FUNCTION (SHOULD USE 20 00, 24 00, OR 26 00) | | 64h 00h R ILLEGAL MODE FOR THIS TRACK | | 28h 01h M IMPORT OR EXPORT ELEMENT ACCESSED | | 30h 00h DT WR OM INCOMPATIBLE MEDIUM INSTALLED | | 11h 08h T INCOMPLETE BLOCK READ | | 48h 00h DTLPWRSOMC INITIATOR DETECTED ERROR MESSAGE RECEIVED | | 3Fh 03h DTLPWRSOMC INQUIRY DATA HAS CHANGED | | 44h 00h DTLPWRSOMC INTERNAL TARGET FAILURE | | 3Dh 00h DTLPWRSOMC INVALID BITS IN IDENTIFY MESSAGE | | 2Ch 02h S INVALID COMBINATION OF WINDOWS SPECIFIED | | 20h 00h DTLPWRSOMC INVALID COMMAND OPERATION CODE | | 21h 01h M INVALID ELEMENT ADDRESS | | 24h 00h DTLPWRSOMC INVALID FIELD IN CDB | | 26h 00h DTLPWRSOMC INVALID FIELD IN PARAMETER LIST | | 49h 00h DTLPWRSOMC INVALID MESSAGE ERROR | | 11h 05h WR O L-EC UNCORRECTABLE ERROR | | 60h 00h S LAMP FAILURE | | 5Bh 02h DTLPWRSOM LOG COUNTER AT MAXIMUM | | 5Bh 00h DTLPWRSOM LOG EXCEPTION | | 5Bh 03h DTLPWRSOM LOG LIST CODES EXHAUSTED | | 2Ah 02h DTL WRSOMC LOG PARAMETERS CHANGED | | 21h 00h DT WR OM LOGICAL BLOCK ADDRESS OUT OF RANGE | | 08h 00h DTL WRSOMC LOGICAL UNIT COMMUNICATION FAILURE | | 08h 02h DTL WRSOMC LOGICAL UNIT COMMUNICATION PARITY ERROR | | 08h 01h DTL WRSOMC LOGICAL UNIT COMMUNICATION TIME-OUT | | 4Ch 00h DTLPWRSOMC LOGICAL UNIT FAILED SELF-CONFIGURATION | | 3Eh 00h DTLPWRSOMC LOGICAL UNIT HAS NOT SELF-CONFIGURED YET | | 04h 01h DTLPWRSOMC LOGICAL UNIT IS IN PROCESS OF BECOMING READY | | 04h 00h DTLPWRSOMC LOGICAL UNIT NOT READY, CAUSE NOT REPORTABLE | | 04h 04h DTL O LOGICAL UNIT NOT READY, FORMAT IN PROGRESS | | 04h 02h DTLPWRSOMC LOGICAL UNIT NOT READY, INITIALIZING COMMAND REQUIRED | | 04h 03h DTLPWRSOMC LOGICAL UNIT NOT READY, MANUAL INTERVENTION REQUIRED | | 25h 00h DTLPWRSOMC LOGICAL UNIT NOT SUPPORTED | | 15h 01h DTL WRSOM MECHANICAL POSITIONING ERROR | | 53h 00h DTL WRSOM MEDIA LOAD OR EJECT FAILED | | 3Bh 0Dh M MEDIUM DESTINATION ELEMENT FULL | | 31h 00h DT W O MEDIUM FORMAT CORRUPTED | | 3Ah 00h DTL WRSOM MEDIUM NOT PRESENT | | 53h 02h DT WR OM MEDIUM REMOVAL PREVENTED | | 3Bh 0Eh M MEDIUM SOURCE ELEMENT EMPTY | | 43h 00h DTLPWRSOMC MESSAGE ERROR | | 3Fh 01h DTLPWRSOMC MICROCODE HAS BEEN CHANGED | | 1Dh 00h D W O MISCOMPARE DURING VERIFY OPERATION | | 11h 0Ah DT O MISCORRECTED ERROR | | 2Ah 01h DTL WRSOMC MODE PARAMETERS CHANGED | | 07h 00h DTL WRSOM MULTIPLE PERIPHERAL DEVICES SELECTED | | 11h 03h DT W SO MULTIPLE READ ERRORS | | 00h 00h DTLPWRSOMC NO ADDITIONAL SENSE INFORMATION | | 00h 15h R NO CURRENT AUDIO STATUS TO RETURN | | 32h 00h D W O NO DEFECT SPARE LOCATION AVAILABLE | | 11h 09h T NO GAP FOUND | | 01h 00h D W O NO INDEX/SECTOR SIGNAL | | 06h 00h D WR OM NO REFERENCE POSITION FOUND | +=============================================================================+ Table 71: (continued) +=============================================================================+ | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 02h 00h D WR OM NO SEEK COMPLETE | | 03h 01h T NO WRITE CURRENT | | 28h 00h DTLPWRSOMC NOT READY TO READY TRANSITION, MEDIUM MAY HAVE CHANGED| | 5Ah 01h DT WR OM OPERATOR MEDIUM REMOVAL REQUEST | | 5Ah 00h DTLPWRSOM OPERATOR REQUEST OR STATE CHANGE INPUT (UNSPECIFIED) | | 5Ah 03h DT W O OPERATOR SELECTED WRITE PERMIT | | 5Ah 02h DT W O OPERATOR SELECTED WRITE PROTECT | | 61h 02h S OUT OF FOCUS | | 4Eh 00h DTLPWRSOMC OVERLAPPED COMMANDS ATTEMPTED | | 2Dh 00h T OVERWRITE ERROR ON UPDATE IN PLACE | | 3Bh 05h L PAPER JAM | | 1Ah 00h DTLPWRSOMC PARAMETER LIST LENGTH ERROR | | 26h 01h DTLPWRSOMC PARAMETER NOT SUPPORTED | | 26h 02h DTLPWRSOMC PARAMETER VALUE INVALID | | 2Ah 00h DTL WRSOMC PARAMETERS CHANGED | | 03h 00h DTL W SO PERIPHERAL DEVICE WRITE FAULT | | 50h 02h T POSITION ERROR RELATED TO TIMING | | 3Bh 0Ch S POSITION PAST BEGINNING OF MEDIUM | | 3Bh 0Bh S POSITION PAST END OF MEDIUM | | 15h 02h DT WR O POSITIONING ERROR DETECTED BY READ OF MEDIUM | | 29h 00h DTLPWRSOMC POWER ON, RESET, OR BUS DEVICE RESET OCCURRED | | 42h 00h D POWER-ON OR SELF-TEST FAILURE (SHOULD USE 40 NN) | | 1Ch 01h D O PRIMARY DEFECT LIST NOT FOUND | | 40h 00h D RAM FAILURE (SHOULD USE 40 NN) | | 15h 00h DTL WRSOM RANDOM POSITIONING ERROR | | 3Bh 0Ah S READ PAST BEGINNING OF MEDIUM | | 3Bh 09h S READ PAST END OF MEDIUM | | 11h 01h DT W SO READ RETRIES EXHAUSTED | | 14h 01h DT WR O RECORD NOT FOUND | | 14h 00h DTL WRSO RECORDED ENTITY NOT FOUND | | 18h 02h D WR O RECOVERED DATA - DATA AUTO-REALLOCATED | | 18h 05h D WR O RECOVERED DATA - RECOMMEND REASSIGNMENT | | 18h 06h D WR O RECOVERED DATA - RECOMMEND REWRITE | | 17h 05h D WR O RECOVERED DATA USING PREVIOUS SECTOR ID | | 18h 03h R RECOVERED DATA WITH CIRC | | 18h 01h D WR O RECOVERED DATA WITH ERROR CORRECTION & RETRIES APPLIED| | 18h 00h DT WR O RECOVERED DATA WITH ERROR CORRECTION APPLIED | | 18h 04h R RECOVERED DATA WITH L-EC | | 17h 03h DT WR O RECOVERED DATA WITH NEGATIVE HEAD OFFSET | | 17h 00h DT WRSO RECOVERED DATA WITH NO ERROR CORRECTION APPLIED | | 17h 02h DT WR O RECOVERED DATA WITH POSITIVE HEAD OFFSET | | 17h 01h DT WRSO RECOVERED DATA WITH RETRIES | | 17h 04h WR O RECOVERED DATA WITH RETRIES AND/OR CIRC APPLIED | | 17h 06h D W O RECOVERED DATA WITHOUT ECC - DATA AUTO-REALLOCATED | | 17h 07h D W O RECOVERED DATA WITHOUT ECC - RECOMMEND REASSIGNMENT | | 17h 08h D W O RECOVERED DATA WITHOUT ECC - RECOMMEND REWRITE | | 1Eh 00h D W O RECOVERED ID WITH ECC CORRECTION | | 3Bh 08h T REPOSITION ERROR | | 36h 00h L RIBBON, INK, OR TONER FAILURE | | 37h 00h DTL WRSOMC ROUNDED PARAMETER | | 5Ch 00h D O RPL STATUS CHANGE | | 39h 00h DTL WRSOMC SAVING PARAMETERS NOT SUPPORTED | | 62h 00h S SCAN HEAD POSITIONING ERROR | | 47h 00h DTLPWRSOMC SCSI PARITY ERROR | | 54h 00h P SCSI TO HOST SYSTEM INTERFACE FAILURE | | 45h 00h DTLPWRSOMC SELECT OR RESELECT FAILURE | +=============================================================================+ Table 71: (concluded) +=============================================================================+ | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 3Bh 00h TL SEQUENTIAL POSITIONING ERROR | | 00h 03h T SETMARK DETECTED | | 3Bh 04h L SLEW FAILURE | | 09h 03h WR O SPINDLE SERVO FAILURE | | 5Ch 02h D O SPINDLES NOT SYNCHRONIZED | | 5Ch 01h D O SPINDLES SYNCHRONIZED | | 1Bh 00h DTLPWRSOMC SYNCHRONOUS DATA TRANSFER ERROR | | 55h 00h P SYSTEM RESOURCE FAILURE | | 33h 00h T TAPE LENGTH ERROR | | 3Bh 03h L TAPE OR ELECTRONIC VERTICAL FORMS UNIT NOT READY | | 3Bh 01h T TAPE POSITION ERROR AT BEGINNING-OF-MEDIUM | | 3Bh 02h T TAPE POSITION ERROR AT END-OF-MEDIUM | | 3Fh 00h DTLPWRSOMC TARGET OPERATING CONDITIONS HAVE CHANGED | | 5Bh 01h DTLPWRSOM THRESHOLD CONDITION MET | | 26h 03h DTLPWRSOMC THRESHOLD PARAMETERS NOT SUPPORTED | | 2Ch 01h S TOO MANY WINDOWS SPECIFIED | | 09h 00h DT WR O TRACK FOLLOWING ERROR | | 09h 01h WR O TRACKING SERVO FAILURE | | 61h 01h S UNABLE TO ACQUIRE VIDEO | | 57h 00h R UNABLE TO RECOVER TABLE-OF-CONTENTS | | 53h 01h T UNLOAD TAPE FAILURE | | 11h 00h DT WRSO UNRECOVERED READ ERROR | | 11h 04h D W O UNRECOVERED READ ERROR - AUTO REALLOCATE FAILED | | 11h 0Bh D W O UNRECOVERED READ ERROR - RECOMMEND REASSIGNMENT | | 11h 0Ch D W O UNRECOVERED READ ERROR - RECOMMEND REWRITE THE DATA | | 46h 00h DTLPWRSOMC UNSUCCESSFUL SOFT RESET | | 59h 00h O UPDATED BLOCK READ | | 61h 00h S VIDEO ACQUISITION ERROR | | 50h 00h T WRITE APPEND ERROR | | 50h 01h T WRITE APPEND POSITION ERROR | | 0Ch 00h T S WRITE ERROR | | 0Ch 02h D W O WRITE ERROR - AUTO REALLOCATION FAILED | | 0Ch 01h D W O WRITE ERROR RECOVERED WITH AUTO REALLOCATION | | 27h 00h DT W O WRITE PROTECTED | | | | 80h XXh \ | | THROUGH > VENDOR SPECIFIC. | | FFh XX / | | | | XXh 80h \ | | THROUGH > VENDOR SPECIFIC QUALIFICATION OF STANDARD ASC. | | XXh FFh / | | ALL CODES NOT SHOWN ARE RESERVED. | |-----------------------------------------------------------------------------| T.2. ASC and ASCQ in numerical order Table 364: ASC and ASCQ Assignments +=============================================================================+ | D - DIRECT ACCESS DEVICE | | .T - SEQUENTIAL ACCESS DEVICE | | . L - PRINTER DEVICE | | . P - PROCESSOR DEVICE | | . .W - WRITE ONCE READ MULTIPLE DEVICE | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 00 00 DTLPWRSOMC NO ADDITIONAL SENSE INFORMATION | | 00 01 T FILEMARK DETECTED | | 00 02 T S END-OF-PARTITION/MEDIUM DETECTED | | 00 03 T SETMARK DETECTED | | 00 04 T S BEGINNING-OF-PARTITION/MEDIUM DETECTED | | 00 05 T S END-OF-DATA DETECTED | | 00 06 DTLPWRSOMC I/O PROCESS TERMINATED | | 00 11 R AUDIO PLAY OPERATION IN PROGRESS | | 00 12 R AUDIO PLAY OPERATION PAUSED | | 00 13 R AUDIO PLAY OPERATION SUCCESSFULLY COMPLETED | | 00 14 R AUDIO PLAY OPERATION STOPPED DUE TO ERROR | | 00 15 R NO CURRENT AUDIO STATUS TO RETURN | | 01 00 DW O NO INDEX/SECTOR SIGNAL | | 02 00 DWR OM NO SEEK COMPLETE | | 03 00 DTL W SO PERIPHERAL DEVICE WRITE FAULT | | 03 01 T NO WRITE CURRENT | | 03 02 T EXCESSIVE WRITE ERRORS | | 04 00 DTLPWRSOMC LOGICAL UNIT NOT READY, CAUSE NOT REPORTABLE | | 04 01 DTLPWRSOMC LOGICAL UNIT IS IN PROCESS OF BECOMING READY | | 04 02 DTLPWRSOMC LOGICAL UNIT NOT READY, INITIALIZING COMMAND REQUIRED | | 04 03 DTLPWRSOMC LOGICAL UNIT NOT READY, MANUAL INTERVENTION REQUIRED | | 04 04 DTL O LOGICAL UNIT NOT READY, FORMAT IN PROGRESS | | 05 00 DTL WRSOMC LOGICAL UNIT DOES NOT RESPOND TO SELECTION | | 06 00 DWR OM NO REFERENCE POSITION FOUND | | 07 00 DTL WRSOM MULTIPLE PERIPHERAL DEVICES SELECTED | | 08 00 DTL WRSOMC LOGICAL UNIT COMMUNICATION FAILURE | | 08 01 DTL WRSOMC LOGICAL UNIT COMMUNICATION TIME-OUT | | 08 02 DTL WRSOMC LOGICAL UNIT COMMUNICATION PARITY ERROR | | 09 00 DT WR O TRACK FOLLOWING ERROR | | 09 01 WR O TRA CKING SERVO FAILURE | | 09 02 WR O FOC US SERVO FAILURE | | 09 03 WR O SPI NDLE SERVO FAILURE | +=============================================================================+ Table 364: (continued) +=============================================================================+ | D - DIRECT ACCESS DEVICE | | .T - SEQUENTIAL ACCESS DEVICE | | . L - PRINTER DEVICE | | . P - PROCESSOR DEVICE | | . .W - WRITE ONCE READ MULTIPLE DEVICE | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 0A 00 DTLPWRSOMC ERROR LOG OVERFLOW | | 0B 00 | | 0C 00 T S WRITE ERROR | | 0C 01 D W O WRITE ERROR RECOVERED WITH AUTO REALLOCATION | | 0C 02 D W O WRITE ERROR - AUTO REALLOCATION FAILED | | 0D 00 | | 0E 00 | | 0F 00 | | 10 00 D W O ID CRC OR ECC ERROR | | 11 00 DT WRSO UNRECOVERED READ ERROR | | 11 01 DT W SO READ RETRIES EXHAUSTED | | 11 02 DT W SO ERROR TOO LONG TO CORRECT | | 11 03 DT W SO MULTIPLE READ ERRORS | | 11 04 D W O UNRECOVERED READ ERROR - AUTO REALLOCATE FAILED | | 11 05 WR O L-EC UNCORRECTABLE ERROR | | 11 06 WR O CIRC UNRECOVERED ERROR | | 11 07 W O DATA RESYCHRONIZATION ERROR | | 11 08 T INCOMPLETE BLOCK READ | | 11 09 T NO GAP FOUND | | 11 0A DT O MISCORRECTED ERROR | | 11 0B D W O UNRECOVERED READ ERROR - RECOMMEND REASSIGNMENT | | 11 0C D W O UNRECOVERED READ ERROR - RECOMMEND REWRITE THE DATA | | 12 00 D W O ADDRESS MARK NOT FOUND FOR ID FIELD | | 13 00 D W O ADDRESS MARK NOT FOUND FOR DATA FIELD | | 14 00 DTL WRSO RECORDED ENTITY NOT FOUND | | 14 01 DT WR O RECORD NOT FOUND | | 14 02 T FILEMARK OR SETMARK NOT FOUND | | 14 03 T END-OF-DATA NOT FOUND | | 14 04 T BLOCK SEQUENCE ERROR | | 15 00 DTL WRSOM RANDOM POSITIONING ERROR | | 15 01 DTL WRSOM MECHANICAL POSITIONING ERROR | | 15 02 DT WR O POSITIONING ERROR DETECTED BY READ OF MEDIUM | | 16 00 DW O DATA SYNCHRONIZATION MARK ERROR | | 17 00 DT WRSO RECOVERED DATA WITH NO ERROR CORRECTION APPLIED | | 17 01 DT WRSO RECOVERED DATA WITH RETRIES | | 17 02 DT WR O RECOVERED DATA WITH POSITIVE HEAD OFFSET | | 17 03 DT WR O RECOVERED DATA WITH NEGATIVE HEAD OFFSET | | 17 04 WR O RECOVERED DATA WITH RETRIES AND/OR CIRC APPLIED | | 17 05 D WR O RECOVERED DATA USING PREVIOUS SECTOR ID | | 17 06 D W O RECOVERED DATA WITHOUT ECC - DATA AUTO-REALLOCATED | | 17 07 D W O RECOVERED DATA WITHOUT ECC - RECOMMEND REASSIGNMENT | | 17 08 D W O RECOVERED DATA WITHOUT ECC - RECOMMEND REWRITE | | 18 00 DT WR O RECOVERED DATA WITH ERROR CORRECTION APPLIED | | 18 01 D WR O RECOVERED DATA WITH ERROR CORRECTION & RETRIES APPLIED| | 18 02 D WR O RECOVERED DATA - DATA AUTO-REALLOCATED | | 18 03 R RECOVERED DATA WITH CIRC | | 18 04 R RECOVERED DATA WITH LEC | | 18 05 D WR O RECOVERED DATA - RECOMMEND REASSIGNMENT | | 18 06 D WR O RECOVERED DATA - RECOMMEND REWRITE | +=============================================================================+ Table 364: (continued) +=============================================================================+ | D - DIRECT ACCESS DEVICE | | .T - SEQUENTIAL ACCESS DEVICE | | . L - PRINTER DEVICE | | . P - PROCESSOR DEVICE | | . .W - WRITE ONCE READ MULTIPLE DEVICE | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 19 00 D O DEFECT LIST ERROR | | 19 01 D O DEFECT LIST NOT AVAILABLE | | 19 02 D O DEFECT LIST ERROR IN PRIMARY LIST | | 19 03 D O DEFECT LIST ERROR IN GROWN LIST | | 1A 00 DTLPWRSOMC PARAMETER LIST LENGTH ERROR | | 1B 00 DTLPWRSOMC SYNCHRONOUS DATA TRANSFER ERROR | | 1C 00 D O DEFECT LIST NOT FOUND | | 1C 01 D O PRIMARY DEFECT LIST NOT FOUND | | 1C 02 D O GROWN DEFECT LIST NOT FOUND | | 1D 00 D W O MISCOMPARE DURING VERIFY OPERATION | | 1E 00 D W O RECOVERED ID WITH ECC | | 1F 00 | | 20 00 DTLPWRSOMC INVALID COMMAND OPERATION CODE | | 21 00 DT WR OM LOGICAL BLOCK ADDRESS OUT OF RANGE | | 21 01 M INVALID ELEMENT ADDRESS | | 22 00 D ILLEGAL FUNCTION (SHOULD USE 20 00, 24 00, OR 26 00) | | 23 00 | | 24 00 DTLPWRSOMC INVALID FIELD IN CDB | | 25 00 DTLPWRSOMC LOGICAL UNIT NOT SUPPORTED | | 26 00 DTLPWRSOMC INVALID FIELD IN PARAMETER LIST | | 26 01 DTLPWRSOMC PARAMETER NOT SUPPORTED | | 26 02 DTLPWRSOMC PARAMETER VALUE INVALID | | 26 03 DTLPWRSOMC THRESHOLD PARAMETERS NOT SUPPORTED | | 27 00 DT W O WRITE PROTECTED | | 28 00 DTLPWRSOMC NOT READY TO READY TRANSITION(MEDIUM MAY HAVE CHANGED)| | 28 01 M IMPORT OR EXPORT ELEMENT ACCESSED | | 29 00 DTLPWRSOMC POWER ON, RESET, OR BUS DEVICE RESET OCCURRED | | 2A 00 DTL WRSOMC PARAMETERS CHANGED | | 2A 01 DTL WRSOMC MODE PARAMETERS CHANGED | | 2A 02 DTL WRSOMC LOG PARAMETERS CHANGED | | 2B 00 DTLPWRSO C COPY CANNOT EXECUTE SINCE HOST CANNOT DISCONNECT | | 2C 00 DTLPWRSOMC COMMAND SEQUENCE ERROR | | 2C 01 S TOO MANY WINDOWS SPECIFIED | | 2C 02 S INVALID COMBINATION OF WINDOWS SPECIFIED | | 2D 00 T OVERWRITE ERROR ON UPDATE IN PLACE | | 2E 00 | | 2F 00 DTLPWRSOMC COMMANDS CLEARED BY ANOTHER INITIATOR | | 30 00 DT WR OM INCOMPATIBLE MEDIUM INSTALLED | | 30 01 DT WR O CANNOT READ MEDIUM - UNKNOWN FORMAT | | 30 02 DT WR O CANNOT READ MEDIUM - INCOMPATIBLE FORMAT | | 30 03 DT CLEANING CARTRIDGE INSTALLED | | 31 00 DT W O MEDIUM FORMAT CORRUPTED | | 31 01 D L O FORMAT COMMAND FAILED | | 32 00 D W O NO DEFECT SPARE LOCATION AVAILABLE | | 32 01 D W O DEFECT LIST UPDATE FAILURE | | 33 00 T TAPE LENGTH ERROR | | 34 00 | | 35 00 | | 36 00 L RIBBON, INK, OR TONER FAILURE | +=============================================================================+ Table 364: (continued) +=============================================================================+ | D - DIRECT ACCESS DEVICE | | .T - SEQUENTIAL ACCESS DEVICE | | . L - PRINTER DEVICE | | . P - PROCESSOR DEVICE | | . .W - WRITE ONCE READ MULTIPLE DEVICE | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 37 00 DTL WRSOMC ROUNDED PARAMETER | | 38 00 | | 39 00 DTL WRSOMC SAVING PARAMETERS NOT SUPPORTED | | 3A 00 DTL WRSOM MEDIUM NOT PRESENT | | 3B 00 TL SEQUENTIAL POSITIONING ERROR | | 3B 01 T TAPE POSITION ERROR AT BEGINNING-OF-MEDIUM | | 3B 02 T TAPE POSITION ERROR AT END-OF-MEDIUM | | 3B 03 L TAPE OR ELECTRONIC VERTICAL FORMS UNIT NOT READY | | 3B 04 L SLEW FAILURE | | 3B 05 L PAPER JAM | | 3B 06 L FAILED TO SENSE TOP-OF-FORM | | 3B 07 L FAILED TO SENSE BOTTOM-OF-FORM | | 3B 08 T REPOSITION ERROR | | 3B 09 S READ PAST END OF MEDIUM | | 3B 0A S READ PAST BEGINNING OF MEDIUM | | 3B 0B S POSITION PAST END OF MEDIUM | | 3B 0C S POSITION PAST BEGINNING OF MEDIUM | | 3B 0D M MEDIUM DESTINATION ELEMENT FULL | | 3B 0E M MEDIUM SOURCE ELEMENT EMPTY | | 3C 00 | | 3D 00 DTLPWRSOMC INVALID BITS IN IDENTIFY MESSAGE | | 3E 00 DTLPWRSOMC LOGICAL UNIT HAS NOT SELF-CONFIGURED YET | | 3F 00 DTLPWRSOMC TARGET OPERATING CONDITIONS HAVE CHANGED | | 3F 01 DTLPWRSOMC MICROCODE HAS BEEN CHANGED | | 3F 02 DTLPWRSOMC CHANGED OPERATING DEFINITION | | 3F 03 DTLPWRSOMC INQUIRY DATA HAS CHANGED | | 40 00 D RAM FAILURE (SHOULD USE 40 NN) | | 40 NN DTLPWRSOMC DIAGNOSTIC FAILURE ON COMPONENT NN (80H-FFH) | | 41 00 D DATA PATH FAILURE (SHOULD USE 40 NN) | | 42 00 D POWER-ON OR SELF-TEST FAILURE (SHOULD USE 40 NN) | | 43 00 DTLPWRSOMC MESSAGE ERROR | | 44 00 DTLPWRSOMC INTERNAL TARGET FAILURE | | 45 00 DTLPWRSOMC SELECT OR RESELECT FAILURE | | 46 00 DTLPWRSOMC UNSUCCESSFUL SOFT RESET | | 47 00 DTLPWRSOMC SCSI PARITY ERROR | | 48 00 DTLPWRSOMC INITIATOR DETECTED ERROR MESSAGE RECEIVED | | 49 00 DTLPWRSOMC INVALID MESSAGE ERROR | | 4A 00 DTLPWRSOMC COMMAND PHASE ERROR | | 4B 00 DTLPWRSOMC DATA PHASE ERROR | | 4C 00 DTLPWRSOMC LOGICAL UNIT FAILED SELF-CONFIGURATION | | 4D 00 | | 4E 00 DTLPWRSOMC OVERLAPPED COMMANDS ATTEMPTED | | 4F 00 | | 50 00 T WRITE APPEND ERROR | | 50 01 T WRITE APPEND POSITION ERROR | | 50 02 T POSITION ERROR RELATED TO TIMING | | 51 00 T O ERASE FAILURE | | 52 00 T CARTRIDGE FAULT | +=============================================================================+ Table 364: (continued) +=============================================================================+ | D - DIRECT ACCESS DEVICE | | .T - SEQUENTIAL ACCESS DEVICE | | . L - PRINTER DEVICE | | . P - PROCESSOR DEVICE | | . .W - WRITE ONCE READ MULTIPLE DEVICE | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 53 00 DTL WRSOM MEDIA LOAD OR EJECT FAILED | | 53 01 T UNLOAD TAPE FAILURE | | 53 02 DT WR OM MEDIUM REMOVAL PREVENTED | | 54 00 P SCSI TO HOST SYSTEM INTERFACE FAILURE | | 55 00 P SYSTEM RESOURCE FAILURE | | 56 00 | | 57 00 R UNABLE TO RECOVER TABLE-OF-CONTENTS | | 58 00 O GENERATION DOES NOT EXIST | | 59 00 O UPDATED BLOCK READ | | 5A 00 DTLPWRSOM OPERATOR REQUEST OR STATE CHANGE INPUT (UNSPECIFIED) | | 5A 01 DT WR OM OPERATOR MEDIUM REMOVAL REQUEST | | 5A 02 DT W O OPERATOR SELECTED WRITE PROTECT | | 5A 03 DT W O OPERATOR SELECTED WRITE PERMIT | | 5B 00 DTLPWRSOM LOG EXCEPTION | | 5B 01 DTLPWRSOM THRESHOLD CONDITION MET | | 5B 02 DTLPWRSOM LOG COUNTER AT MAXIMUM | | 5B 03 DTLPWRSOM LOG LIST CODES EXHAUSTED | | 5C 00 D O RPL STATUS CHANGE | | 5C 01 D O SPINDLES SYNCHRONIZED | | 5C 02 D O SPINDLES NOT SYNCHRONIZED | | 5D 00 | | 5E 00 | | 5F 00 | | 60 00 S LAMP FAILURE | | 61 00 S VIDEO ACQUISITION ERROR | | 61 01 S UNABLE TO ACQUIRE VIDEO | | 61 02 S OUT OF FOCUS | | 62 00 S SCAN HEAD POSITIONING ERROR | | 63 00 R END OF USER AREA ENCOUNTERED ON THIS TRACK | | 64 00 R ILLEGAL MODE FOR THIS TRACK | | 65 00 | | 66 00 | | 67 00 | | 68 00 | | 69 00 | | 6A 00 | | 6B 00 | | 6C 00 | | 6D 00 | | 6E 00 | | 6F 00 | +=============================================================================+ Table 364: (concluded) +=============================================================================+ | D - DIRECT ACCESS DEVICE | | .T - SEQUENTIAL ACCESS DEVICE | | . L - PRINTER DEVICE | | . P - PROCESSOR DEVICE | | . .W - WRITE ONCE READ MULTIPLE DEVICE | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | ASC ASCQ DTLPWRSOMC DESCRIPTION | | --- ---- ----------------------------------------------------- | | 70 00 | | 71 00 | | 72 00 | | 73 00 | | 74 00 | | 75 00 | | 76 00 | | 77 00 | | 78 00 | | 79 00 | | 7A 00 | | 7B 00 | | 7C 00 | | 7D 00 | | 7E 00 | | 7F 00 | | | | 80 xxh \ | | THROUGH > VENDOR SPECIFIC. | | FF xxh / | | | | xxh 80 \ | | THROUGH > VENDOR SPECIFIC QUALIFICATION OF STANDARD ASC. | | xxh FF / | | ALL CODES NOT SHOWN OR BLANK ARE RESERVED. | +=============================================================================+ U. A SCSI command code quick reference Table 365 is a numerical order listing of the command operation codes. Table 365: SCSI-2 Operation Codes +=============================================================================+ | D - DIRECT ACCESS DEVICE Device Column Key | | .T - SEQUENTIAL ACCESS DEVICE M = Mandatory | | . L - PRINTER DEVICE O = Optional | | . P - PROCESSOR DEVICE V = Vendor Specific| | . .W - WRITE ONCE READ MULTIPLE DEVICE R = Reserved | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | OP DTLPWRSOMC Description | |----------+----------+-------------------------------------------------------| | 00 MMMMMMMMMM TEST UNIT READY | | 01 M REWIND | | 01 O V OO OO REZERO UNIT | | 02 VVVVVV V | | 03 MMMMMMMMMM REQUEST SENSE | | 04 O FORMAT | | 04 M O FORMAT UNIT | | 05 VMVVVV V READ BLOCK LIMITS | | 06 VVVVVV V | | 07 O INITIALIZE ELEMENT STATUS | | 07 OVV O OV REASSIGN BLOCKS | | 08 M GET MESSAGE(06) | | 08 OMV OO OV READ(06) | | 08 O RECEIVE | | 09 VVVVVV V | | 0A M PRINT | | 0A M SEND MESSAGE(06) | | 0A M SEND(06) | | 0A OM O OV WRITE(06) | | 0B O OO OV SEEK(06) | | 0B O SLEW AND PRINT | | 0C VVVVVV V | | 0D VVVVVV V | | 0E VVVVVV V | | 0F VOVVVV V READ REVERSE | | 10 O O SYNCHRONIZE BUFFER | | 10 VM VVV WRITE FILEMARKS | | 11 VMVVVV SPACE | | 12 MMMMMMMMMM INQUIRY | | 13 VOVVVV VERIFY(06) | | 14 VOOVVV RECOVER BUFFERED DATA | | 15 OMO OOOOOO MODE SELECT(06) | | 16 M MM MO RESERVE | | 16 MM M RESERVE UNIT | | 17 M MM MO RELEASE | | 17 MM M RELEASE UNIT | | 18 OOOOOOOO COPY | | 19 VMVVVV ERASE | | 1A OMO OOOOOO MODE SENSE(06) | | 1B O LOAD UNLOAD | | 1B O SCAN | | 1B O STOP PRINT | | 1B O OO O STOP START UNIT | +=============================================================================+ Table 365: (continued) +=============================================================================+ | D - DIRECT ACCESS DEVICE Device Column Key | | .T - SEQUENTIAL ACCESS DEVICE M = Mandatory | | . L - PRINTER DEVICE O = Optional | | . P - PROCESSOR DEVICE V = Vendor Specific| | . .W - WRITE ONCE READ MULTIPLE DEVICE R = Reserved | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | OP DTLPWRSOMC Description | |----------+----------+-------------------------------------------------------| | 1C OOOOOOOOOO RECEIVE DIAGNOSTIC RESULTS | | 1D MMMMMMMMMM SEND DIAGNOSTIC | | 1E OO OO OO PREVENT ALLOW MEDIUM REMOVAL | | 1F | | 20 V VV V | | 21 V VV V | | 22 V VV V | | 23 V VV V | | 24 V VVM SET WINDOW | | 25 O GET WINDOW | | 25 M M M READ CAPACITY | | 25 M READ CD-ROM CAPACITY | | 26 V VV | | 27 V VV | | 28 O GET MESSAGE(10) | | 28 M MMMM READ(10) | | 29 V VV O READ GENERATION | | 2A O SEND MESSAGE(10) | | 2A O SEND(10) | | 2A M M M WRITE(10) | | 2B O LOCATE | | 2B O POSITION TO ELEMENT | | 2B O OO O SEEK(10) | | 2C V O ERASE(10) | | 2D V O O READ UPDATED BLOCK | | 2E O O O WRITE AND VERIFY(10) | | 2F O OO O VERIFY(10) | | 30 O OO O SEARCH DATA HIGH(10) | | 31 O OBJECT POSITION | | 31 O OO O SEARCH DATA EQUAL(10) | | 32 O OO O SEARCH DATA LOW(10) | | 33 O OO O SET LIMITS(10) | | 34 O GET DATA BUFFER STATUS | | 34 O OO O PRE-FETCH | | 34 O READ POSITION | | 35 O OO O SYNCHRONIZE CACHE | | 36 O OO O LOCK UNLOCK CACHE | | 37 O O READ DEFECT DATA(10) | | 38 O O MEDIUM SCAN | | 39 OOOOOOOO COMPARE | | 3A OOOOOOOO COPY AND VERIFY | | 3B OOOOOOOOOO WRITE BUFFER | | 3C OOOOOOOOOO READ BUFFER | | 3D O O UPDATE BLOCK | | 3E O OO O READ LONG | | 3F O O O WRITE LONG | +=============================================================================+ Table 365: (continued) +=============================================================================+ | D - DIRECT ACCESS DEVICE Device Column Key | | .T - SEQUENTIAL ACCESS DEVICE M = Mandatory | | . L - PRINTER DEVICE O = Optional | | . P - PROCESSOR DEVICE V = Vendor Specific| | . .W - WRITE ONCE READ MULTIPLE DEVICE R = Reserved | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | OP DTLPWRSOMC Description | |----------+----------+-------------------------------------------------------| | 40 OOOOOOOOOO CHANGE DEFINITION | | 41 O WRITE SAME | | 42 O READ SUB-CHANNEL | | 43 O READ TOC | | 44 O READ HEADER | | 45 O PLAY AUDIO(10) | | 46 | | 47 O PLAY AUDIO MSF | | 48 O PLAY AUDIO TRACK INDEX | | 49 O PLAY TRACK RELATIVE(10) | | 4A | | 4B O PAUSE RESUME | | 4C OOOOOOOOOO LOG SELECT | | 4D OOOOOOOOOO LOG SENSE | | 4E | | 4F | | 50 | | 51 | | 52 | | 53 | | 54 | | 55 OOO OOOOOO MODE SELECT(10) | | 56 | | 57 | | 58 | | 59 | | 5A OOO OOOOOO MODE SENSE(10) | | 5B | | 5C | | 5D | | 5E | | 5F | +=============================================================================+ Table 365: (concluded) +=============================================================================+ | D - DIRECT ACCESS DEVICE Device Column Key | | .T - SEQUENTIAL ACCESS DEVICE M = Mandatory | | . L - PRINTER DEVICE O = Optional | | . P - PROCESSOR DEVICE V = Vendor Specific| | . .W - WRITE ONCE READ MULTIPLE DEVICE R = Reserved | | . . R - READ ONLY (CD-ROM) DEVICE | | . . S - SCANNER DEVICE | | . . .O - OPTICAL MEMORY DEVICE | | . . . M - MEDIA CHANGER DEVICE | | . . . C - COMMUNICATION DEVICE | | . . . . | | OP DTLPWRSOMC Description | |----------+----------+-------------------------------------------------------| | A0 | | A1 | | A2 | | A3 | | A4 | | A5 M MOVE MEDIUM | | A5 O PLAY AUDIO(12) | | A6 O EXCHANGE MEDIUM | | A7 | | A8 O GET MESSAGE(12) | | A8 OO O READ(12) | | A9 O PLAY TRACK RELATIVE(12) | | AA O SEND MESSAGE(12) | | AA O O WRITE(12) | | AB | | AC O ERASE(12) | | AD | | AE O O WRITE AND VERIFY(12) | | AF OO O VERIFY(12) | | B0 OO O SEARCH DATA HIGH(12) | | B1 OO O SEARCH DATA EQUAL(12) | | B2 OO O SEARCH DATA LOW(12) | | B3 OO O SET LIMITS(12) | | B4 | | B5 | | B5 O REQUEST VOLUME ELEMENT ADDRESS | | B6 | | B6 O SEND VOLUME TAG | | B7 O READ DEFECT DATA(12) | | B8 | | B8 O READ ELEMENT STATUS | | B9 | | BA | | BB | | BC | | BD | | BE | | BF | +=============================================================================+ V. Example programs Here is the C example program, which requests manufacturer/model and reports if a medium is loaded in the device. /* Example program to demonstrate the generic SCSI interface */ #include #include #include #include #include #include #define DEVICE "/dev/sgc" #define SCSI_OFF sizeof(struct sg_header) static unsigned char cmd[SCSI_OFF + 18]; /* SCSI command buffer */ int fd; /* SCSI device/file descriptor */ /* process a complete scsi cmd. Use the generic scsi interface. */ static int handle_scsi_cmd(unsigned cmd_len, /* command length */ unsigned in_size, /* input data size */ unsigned char *i_buff, /* input buffer */ unsigned out_size, /* output data size */ unsigned char *o_buff /* output buffer */ ) { int status = 0; struct sg_header *sg_hd; /* safety checks */ if (!cmd_len) return -1; /* need a cmd_len != 0 */ if (!i_buff) return -1; /* need an input buffer != NULL */ #ifdef SG_BIG_BUFF if (SCSI_OFF + cmd_len + in_size > SG_BIG_BUFF) return -1; if (SCSI_OFF + out_size > SG_BIG_BUFF) return -1; #else if (SCSI_OFF + cmd_len + in_size > 4096) return -1; if (SCSI_OFF + out_size > 4096) return -1; #endif if (!o_buff) out_size = 0; /* generic scsi device header construction */ sg_hd = (struct sg_header *) i_buff; sg_hd->pack_len = SCSI_OFF + cmd_len + in_size; sg_hd->reply_len = SCSI_OFF + out_size; sg_hd->twelve_byte = cmd_len == 12; #if 0 sg_hd->pack_id; /* not used */ sg_hd->other_flags; /* not used */ #endif /* send command */ status = write( fd, i_buff, SCSI_OFF + cmd_len + in_size ); if ( status < 0 || status != SCSI_OFF + cmd_len + in_size || sg_hd->result ) { /* some error happened */ fprintf( stderr, "write(generic) result = 0x%x cmd = 0x%x\n", sg_hd->result, i_buff[SCSI_OFF] ); perror(""); return status; } if (!o_buff) o_buff = i_buff; /* buffer pointer check */ /* retrieve result */ status = read( fd, o_buff, SCSI_OFF + out_size); if ( status < 0 || status != SCSI_OFF + out_size || sg_hd->result ) { /* some error happened */ fprintf( stderr, "read(generic) result = 0x%x cmd = 0x%x\n", sg_hd->result, o_buff[SCSI_OFF] ); fprintf( stderr, "read(generic) sense " "%x %x %x %x %x %x %x %x %x %x %x %x %x %x %x %x\n", sg_hd->sense_buffer[0], sg_hd->sense_buffer[1], sg_hd->sense_buffer[2], sg_hd->sense_buffer[3], sg_hd->sense_buffer[4], sg_hd->sense_buffer[5], sg_hd->sense_buffer[6], sg_hd->sense_buffer[7], sg_hd->sense_buffer[8], sg_hd->sense_buffer[9], sg_hd->sense_buffer[10], sg_hd->sense_buffer[11], sg_hd->sense_buffer[12], sg_hd->sense_buffer[13], sg_hd->sense_buffer[14], sg_hd->sense_buffer[15]); perror(""); } /* Look if we got what we expected to get */ if (status == SCSI_OFF + out_size) status = 0; /* got them all */ return status; /* 0 means no error */ } #define INQUIRY_CMD 0x12 #define INQUIRY_CMDLEN 6 #define INQUIRY_REPLY_LEN 96 #define INQUIRY_VENDOR 8 /* Offset in reply data to vendor name */ /* request vendor brand and model */ static unsigned char *Inquiry ( void ) { unsigned char Inqbuffer[ SCSI_OFF + INQUIRY_REPLY_LEN ]; unsigned char cmdblk [ INQUIRY_CMDLEN ] = { INQUIRY_CMD, /* command */ 0, /* lun/reserved */ 0, /* page code */ 0, /* reserved */ INQUIRY_REPLY_LEN, /* allocation length */ 0 };/* reserved/flag/link */ memcpy( cmd + SCSI_OFF, cmdblk, sizeof(cmdblk) ); if (handle_scsi_cmd(sizeof(cmdblk), 0, cmd, sizeof(Inqbuffer) - SCSI_OFF, Inqbuffer )) { fprintf( stderr, "Inquiry failed\n" ); exit(2); } return (Inqbuffer + SCSI_OFF); } #define TESTUNITREADY_CMD 0 #define TESTUNITREADY_CMDLEN 6 #define ADD_SENSECODE 12 #define ADD_SC_QUALIFIER 13 #define NO_MEDIA_SC 0x3a #define NO_MEDIA_SCQ 0x00 int TestForMedium ( void ) { /* request READY status */ static unsigned char cmdblk [TESTUNITREADY_CMDLEN] = { TESTUNITREADY_CMD, /* command */ 0, /* reserved */ 0, /* reserved */ 0, /* reserved */ 0, /* reserved */ 0};/* reserved */ memcpy( cmd + SCSI_OFF, cmdblk, sizeof(cmdblk) ); if (handle_scsi_cmd(sizeof(cmdblk), 0, cmd, 0, NULL)) { fprintf (stderr, "Test unit ready failed\n"); exit(2); } return *(((struct sg_header*)cmd)->sense_buffer +ADD_SENSECODE) != NO_MEDIA_SC || *(((struct sg_header*)cmd)->sense_buffer +ADD_SC_QUALIFIER) != NO_MEDIA_SCQ; } void main( void ) { fd = open(DEVICE, O_RDWR); if (fd < 0) { fprintf( stderr, "Need read/write permissions for "DEVICE".\n" ); exit(1); } /* print the result of Inquiry */ printf( "%s\n", Inquiry() + INQUIRY_VENDOR ); /* look if medium is loaded */ if (!TestForMedium()) { printf("device is unloaded\n"); } else { printf("device is loaded\n"); } }