diff options
Diffstat (limited to 'include/scsi/sg.h')
| -rw-r--r-- | include/scsi/sg.h | 92 |
1 files changed, 25 insertions, 67 deletions
diff --git a/include/scsi/sg.h b/include/scsi/sg.h index a9f3c6fc3f57..9859355a7cf9 100644 --- a/include/scsi/sg.h +++ b/include/scsi/sg.h @@ -4,77 +4,34 @@ #include <linux/compiler.h> /* - History: - Started: Aug 9 by Lawrence Foard (entropy@world.std.com), to allow user - process control of SCSI devices. - Development Sponsored by Killy Corp. NY NY -Original driver (sg.h): -* Copyright (C) 1992 Lawrence Foard -Version 2 and 3 extensions to driver: -* Copyright (C) 1998 - 2006 Douglas Gilbert - - Version: 3.5.34 (20060920) - This version is for 2.6 series kernels. - - For a full changelog see http://www.torque.net/sg - -Map of SG verions to the Linux kernels in which they appear: - ---------- ---------------------------------- - original all kernels < 2.2.6 - 2.1.40 2.2.20 - 3.0.x optional version 3 sg driver for 2.2 series - 3.1.17++ 2.4.0++ - 3.5.30++ 2.6.0++ - -Major new features in SG 3.x driver (cf SG 2.x drivers) - - SG_IO ioctl() combines function if write() and read() - - new interface (sg_io_hdr_t) but still supports old interface - - scatter/gather in user space, direct IO, and mmap supported - - The normal action of this driver is to use the adapter (HBA) driver to DMA - data into kernel buffers and then use the CPU to copy the data into the - user space (vice versa for writes). That is called "indirect" IO due to - the double handling of data. There are two methods offered to remove the - redundant copy: 1) direct IO and 2) using the mmap() system call to map - the reserve buffer (this driver has one reserve buffer per fd) into the - user space. Both have their advantages. - In terms of absolute speed mmap() is faster. If speed is not a concern, - indirect IO should be fine. Read the documentation for more information. - - ** N.B. To use direct IO 'echo 1 > /proc/scsi/sg/allow_dio' or - 'echo 1 > /sys/module/sg/parameters/allow_dio' is needed. - That attribute is 0 by default. ** - - Historical note: this SCSI pass-through driver has been known as "sg" for - a decade. In broader kernel discussions "sg" is used to refer to scatter - gather techniques. The context should clarify which "sg" is referred to. - - Documentation - ============= - A web site for the SG device driver can be found at: - http://www.torque.net/sg [alternatively check the MAINTAINERS file] - The documentation for the sg version 3 driver can be found at: - http://www.torque.net/sg/p/sg_v3_ho.html - This is a rendering from DocBook source [change the extension to "sgml" - or "xml"]. There are renderings in "ps", "pdf", "rtf" and "txt" (soon). - The SG_IO ioctl is now found in other parts kernel (e.g. the block layer). - For more information see http://www.torque.net/sg/sg_io.html - - The older, version 2 documents discuss the original sg interface in detail: - http://www.torque.net/sg/p/scsi-generic.txt - http://www.torque.net/sg/p/scsi-generic_long.txt - Also available: <kernel_source>/Documentation/scsi/scsi-generic.txt - - Utility and test programs are available at the sg web site. They are - packaged as sg3_utils (for the lk 2.4 and 2.6 series) and sg_utils - (for the lk 2.2 series). -*/ + * History: + * Started: Aug 9 by Lawrence Foard (entropy@world.std.com), to allow user + * process control of SCSI devices. + * Development Sponsored by Killy Corp. NY NY + * + * Original driver (sg.h): + * Copyright (C) 1992 Lawrence Foard + * Version 2 and 3 extensions to driver: + * Copyright (C) 1998 - 2014 Douglas Gilbert + * + * Version: 3.5.36 (20140603) + * This version is for 2.6 and 3 series kernels. + * + * Documentation + * ============= + * A web site for the SG device driver can be found at: + * http://sg.danny.cz/sg [alternatively check the MAINTAINERS file] + * The documentation for the sg version 3 driver can be found at: + * http://sg.danny.cz/sg/p/sg_v3_ho.html + * Also see: <kernel_source>/Documentation/scsi/scsi-generic.txt + * + * For utility and test programs see: http://sg.danny.cz/sg/sg3_utils.html + */ #ifdef __KERNEL__ extern int sg_big_buff; /* for sysctl */ #endif -/* New interface introduced in the 3.x SG drivers follows */ typedef struct sg_iovec /* same structure as used by readv() Linux system */ { /* call. It defines one scatter-gather element. */ @@ -87,7 +44,7 @@ typedef struct sg_io_hdr { int interface_id; /* [i] 'S' for SCSI generic (required) */ int dxfer_direction; /* [i] data transfer direction */ - unsigned char cmd_len; /* [i] SCSI command length ( <= 16 bytes) */ + unsigned char cmd_len; /* [i] SCSI command length */ unsigned char mx_sb_len; /* [i] max length to write to sbp */ unsigned short iovec_count; /* [i] 0 implies no scatter gather */ unsigned int dxfer_len; /* [i] byte count of data transfer */ @@ -129,6 +86,7 @@ typedef struct sg_io_hdr #define SG_FLAG_MMAP_IO 4 /* request memory mapped IO */ #define SG_FLAG_NO_DXFER 0x10000 /* no transfer of kernel buffers to/from */ /* user space (debug indirect IO) */ +#define SG_FLAG_Q_AT_TAIL 0x10 /* default is Q_AT_HEAD */ /* following 'info' values are "or"-ed together */ #define SG_INFO_OK_MASK 0x1 |