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6460e75a10
This sg driver patch addresses the problem with larger page sizes reported by Brian King in this post: http://marc.theaimsgroup.com/?l=linux-scsi&m=115867718623631&w=2 Some other related matters are also addressed. Some of these prevent oopses when the SG_SCATTER_SZ or scatter_elem_sz are set to inappropriate values. The scatter_elem_sz has been tested up to 4 MB which should make the largest data transfer with one SCSI command, 32 MB less one block, achievable with a relatively small number of elements in the scatter gather list. ChangeLog: - add scatter_elem_sz boot time parameter and sysfs module parameter that is initialized to SG_SCATTER_SZ - the driver will then adjust scatter_elem_sz to be the max(given(scatter_elem_sz), PAGE_SIZE) It will also round it up, if necessary, to be a power of two - clean up sg.h header, correct bad urls and some statements that are no longer valid - make the def_reserved_size sysfs module attribute writable Signed-off-by: Douglas Gilbert <dougg@torque.net> Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
308 lines
14 KiB
C
308 lines
14 KiB
C
#ifndef _SCSI_GENERIC_H
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#define _SCSI_GENERIC_H
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#include <linux/compiler.h>
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/*
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History:
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Started: Aug 9 by Lawrence Foard (entropy@world.std.com), to allow user
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process control of SCSI devices.
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Development Sponsored by Killy Corp. NY NY
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Original driver (sg.h):
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* Copyright (C) 1992 Lawrence Foard
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Version 2 and 3 extensions to driver:
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* Copyright (C) 1998 - 2006 Douglas Gilbert
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Version: 3.5.34 (20060920)
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This version is for 2.6 series kernels.
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For a full changelog see http://www.torque.net/sg
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Map of SG verions to the Linux kernels in which they appear:
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---------- ----------------------------------
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original all kernels < 2.2.6
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2.1.40 2.2.20
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3.0.x optional version 3 sg driver for 2.2 series
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3.1.17++ 2.4.0++
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3.5.30++ 2.6.0++
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Major new features in SG 3.x driver (cf SG 2.x drivers)
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- SG_IO ioctl() combines function if write() and read()
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- new interface (sg_io_hdr_t) but still supports old interface
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- scatter/gather in user space, direct IO, and mmap supported
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The normal action of this driver is to use the adapter (HBA) driver to DMA
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data into kernel buffers and then use the CPU to copy the data into the
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user space (vice versa for writes). That is called "indirect" IO due to
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the double handling of data. There are two methods offered to remove the
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redundant copy: 1) direct IO and 2) using the mmap() system call to map
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the reserve buffer (this driver has one reserve buffer per fd) into the
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user space. Both have their advantages.
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In terms of absolute speed mmap() is faster. If speed is not a concern,
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indirect IO should be fine. Read the documentation for more information.
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** N.B. To use direct IO 'echo 1 > /proc/scsi/sg/allow_dio' or
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'echo 1 > /sys/module/sg/parameters/allow_dio' is needed.
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That attribute is 0 by default. **
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Historical note: this SCSI pass-through driver has been known as "sg" for
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a decade. In broader kernel discussions "sg" is used to refer to scatter
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gather techniques. The context should clarify which "sg" is referred to.
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Documentation
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=============
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A web site for the SG device driver can be found at:
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http://www.torque.net/sg [alternatively check the MAINTAINERS file]
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The documentation for the sg version 3 driver can be found at:
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http://www.torque.net/sg/p/sg_v3_ho.html
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This is a rendering from DocBook source [change the extension to "sgml"
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or "xml"]. There are renderings in "ps", "pdf", "rtf" and "txt" (soon).
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The SG_IO ioctl is now found in other parts kernel (e.g. the block layer).
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For more information see http://www.torque.net/sg/sg_io.html
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The older, version 2 documents discuss the original sg interface in detail:
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http://www.torque.net/sg/p/scsi-generic.txt
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http://www.torque.net/sg/p/scsi-generic_long.txt
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Also available: <kernel_source>/Documentation/scsi/scsi-generic.txt
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Utility and test programs are available at the sg web site. They are
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packaged as sg3_utils (for the lk 2.4 and 2.6 series) and sg_utils
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(for the lk 2.2 series).
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*/
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/* New interface introduced in the 3.x SG drivers follows */
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typedef struct sg_iovec /* same structure as used by readv() Linux system */
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{ /* call. It defines one scatter-gather element. */
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void __user *iov_base; /* Starting address */
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size_t iov_len; /* Length in bytes */
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} sg_iovec_t;
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typedef struct sg_io_hdr
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{
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int interface_id; /* [i] 'S' for SCSI generic (required) */
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int dxfer_direction; /* [i] data transfer direction */
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unsigned char cmd_len; /* [i] SCSI command length ( <= 16 bytes) */
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unsigned char mx_sb_len; /* [i] max length to write to sbp */
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unsigned short iovec_count; /* [i] 0 implies no scatter gather */
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unsigned int dxfer_len; /* [i] byte count of data transfer */
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void __user *dxferp; /* [i], [*io] points to data transfer memory
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or scatter gather list */
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unsigned char __user *cmdp; /* [i], [*i] points to command to perform */
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void __user *sbp; /* [i], [*o] points to sense_buffer memory */
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unsigned int timeout; /* [i] MAX_UINT->no timeout (unit: millisec) */
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unsigned int flags; /* [i] 0 -> default, see SG_FLAG... */
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int pack_id; /* [i->o] unused internally (normally) */
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void __user * usr_ptr; /* [i->o] unused internally */
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unsigned char status; /* [o] scsi status */
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unsigned char masked_status;/* [o] shifted, masked scsi status */
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unsigned char msg_status; /* [o] messaging level data (optional) */
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unsigned char sb_len_wr; /* [o] byte count actually written to sbp */
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unsigned short host_status; /* [o] errors from host adapter */
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unsigned short driver_status;/* [o] errors from software driver */
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int resid; /* [o] dxfer_len - actual_transferred */
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unsigned int duration; /* [o] time taken by cmd (unit: millisec) */
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unsigned int info; /* [o] auxiliary information */
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} sg_io_hdr_t; /* 64 bytes long (on i386) */
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#define SG_INTERFACE_ID_ORIG 'S'
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/* Use negative values to flag difference from original sg_header structure */
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#define SG_DXFER_NONE (-1) /* e.g. a SCSI Test Unit Ready command */
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#define SG_DXFER_TO_DEV (-2) /* e.g. a SCSI WRITE command */
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#define SG_DXFER_FROM_DEV (-3) /* e.g. a SCSI READ command */
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#define SG_DXFER_TO_FROM_DEV (-4) /* treated like SG_DXFER_FROM_DEV with the
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additional property than during indirect
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IO the user buffer is copied into the
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kernel buffers before the transfer */
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#define SG_DXFER_UNKNOWN (-5) /* Unknown data direction */
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/* following flag values can be "or"-ed together */
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#define SG_FLAG_DIRECT_IO 1 /* default is indirect IO */
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#define SG_FLAG_UNUSED_LUN_INHIBIT 2 /* default is overwrite lun in SCSI */
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/* command block (when <= SCSI_2) */
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#define SG_FLAG_MMAP_IO 4 /* request memory mapped IO */
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#define SG_FLAG_NO_DXFER 0x10000 /* no transfer of kernel buffers to/from */
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/* user space (debug indirect IO) */
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/* following 'info' values are "or"-ed together */
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#define SG_INFO_OK_MASK 0x1
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#define SG_INFO_OK 0x0 /* no sense, host nor driver "noise" */
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#define SG_INFO_CHECK 0x1 /* something abnormal happened */
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#define SG_INFO_DIRECT_IO_MASK 0x6
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#define SG_INFO_INDIRECT_IO 0x0 /* data xfer via kernel buffers (or no xfer) */
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#define SG_INFO_DIRECT_IO 0x2 /* direct IO requested and performed */
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#define SG_INFO_MIXED_IO 0x4 /* part direct, part indirect IO */
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typedef struct sg_scsi_id { /* used by SG_GET_SCSI_ID ioctl() */
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int host_no; /* as in "scsi<n>" where 'n' is one of 0, 1, 2 etc */
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int channel;
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int scsi_id; /* scsi id of target device */
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int lun;
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int scsi_type; /* TYPE_... defined in scsi/scsi.h */
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short h_cmd_per_lun;/* host (adapter) maximum commands per lun */
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short d_queue_depth;/* device (or adapter) maximum queue length */
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int unused[2]; /* probably find a good use, set 0 for now */
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} sg_scsi_id_t; /* 32 bytes long on i386 */
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typedef struct sg_req_info { /* used by SG_GET_REQUEST_TABLE ioctl() */
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char req_state; /* 0 -> not used, 1 -> written, 2 -> ready to read */
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char orphan; /* 0 -> normal request, 1 -> from interruped SG_IO */
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char sg_io_owned; /* 0 -> complete with read(), 1 -> owned by SG_IO */
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char problem; /* 0 -> no problem detected, 1 -> error to report */
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int pack_id; /* pack_id associated with request */
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void __user *usr_ptr; /* user provided pointer (in new interface) */
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unsigned int duration; /* millisecs elapsed since written (req_state==1)
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or request duration (req_state==2) */
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int unused;
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} sg_req_info_t; /* 20 bytes long on i386 */
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/* IOCTLs: Those ioctls that are relevant to the SG 3.x drivers follow.
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[Those that only apply to the SG 2.x drivers are at the end of the file.]
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(_GET_s yield result via 'int *' 3rd argument unless otherwise indicated) */
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#define SG_EMULATED_HOST 0x2203 /* true for emulated host adapter (ATAPI) */
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/* Used to configure SCSI command transformation layer for ATAPI devices */
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/* Only supported by the ide-scsi driver */
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#define SG_SET_TRANSFORM 0x2204 /* N.B. 3rd arg is not pointer but value: */
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/* 3rd arg = 0 to disable transform, 1 to enable it */
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#define SG_GET_TRANSFORM 0x2205
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#define SG_SET_RESERVED_SIZE 0x2275 /* request a new reserved buffer size */
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#define SG_GET_RESERVED_SIZE 0x2272 /* actual size of reserved buffer */
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/* The following ioctl has a 'sg_scsi_id_t *' object as its 3rd argument. */
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#define SG_GET_SCSI_ID 0x2276 /* Yields fd's bus, chan, dev, lun + type */
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/* SCSI id information can also be obtained from SCSI_IOCTL_GET_IDLUN */
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/* Override host setting and always DMA using low memory ( <16MB on i386) */
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#define SG_SET_FORCE_LOW_DMA 0x2279 /* 0-> use adapter setting, 1-> force */
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#define SG_GET_LOW_DMA 0x227a /* 0-> use all ram for dma; 1-> low dma ram */
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/* When SG_SET_FORCE_PACK_ID set to 1, pack_id is input to read() which
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tries to fetch a packet with a matching pack_id, waits, or returns EAGAIN.
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If pack_id is -1 then read oldest waiting. When ...FORCE_PACK_ID set to 0
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then pack_id ignored by read() and oldest readable fetched. */
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#define SG_SET_FORCE_PACK_ID 0x227b
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#define SG_GET_PACK_ID 0x227c /* Yields oldest readable pack_id (or -1) */
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#define SG_GET_NUM_WAITING 0x227d /* Number of commands awaiting read() */
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/* Yields max scatter gather tablesize allowed by current host adapter */
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#define SG_GET_SG_TABLESIZE 0x227F /* 0 implies can't do scatter gather */
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#define SG_GET_VERSION_NUM 0x2282 /* Example: version 2.1.34 yields 20134 */
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/* Returns -EBUSY if occupied. 3rd argument pointer to int (see next) */
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#define SG_SCSI_RESET 0x2284
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/* Associated values that can be given to SG_SCSI_RESET follow */
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#define SG_SCSI_RESET_NOTHING 0
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#define SG_SCSI_RESET_DEVICE 1
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#define SG_SCSI_RESET_BUS 2
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#define SG_SCSI_RESET_HOST 3
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/* synchronous SCSI command ioctl, (only in version 3 interface) */
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#define SG_IO 0x2285 /* similar effect as write() followed by read() */
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#define SG_GET_REQUEST_TABLE 0x2286 /* yields table of active requests */
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/* How to treat EINTR during SG_IO ioctl(), only in SG 3.x series */
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#define SG_SET_KEEP_ORPHAN 0x2287 /* 1 -> hold for read(), 0 -> drop (def) */
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#define SG_GET_KEEP_ORPHAN 0x2288
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/* yields scsi midlevel's access_count for this SCSI device */
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#define SG_GET_ACCESS_COUNT 0x2289
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#define SG_SCATTER_SZ (8 * 4096)
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/* Largest size (in bytes) a single scatter-gather list element can have.
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The value used by the driver is 'max(SG_SCATTER_SZ, PAGE_SIZE)'.
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This value should be a power of 2 (and may be rounded up internally).
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If scatter-gather is not supported by adapter then this value is the
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largest data block that can be read/written by a single scsi command. */
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#define SG_DEFAULT_RETRIES 0
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/* Defaults, commented if they differ from original sg driver */
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#define SG_DEF_FORCE_LOW_DMA 0 /* was 1 -> memory below 16MB on i386 */
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#define SG_DEF_FORCE_PACK_ID 0
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#define SG_DEF_KEEP_ORPHAN 0
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#define SG_DEF_RESERVED_SIZE SG_SCATTER_SZ /* load time option */
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/* maximum outstanding requests, write() yields EDOM if exceeded */
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#define SG_MAX_QUEUE 16
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#define SG_BIG_BUFF SG_DEF_RESERVED_SIZE /* for backward compatibility */
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/* Alternate style type names, "..._t" variants preferred */
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typedef struct sg_io_hdr Sg_io_hdr;
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typedef struct sg_io_vec Sg_io_vec;
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typedef struct sg_scsi_id Sg_scsi_id;
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typedef struct sg_req_info Sg_req_info;
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/* vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv */
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/* The older SG interface based on the 'sg_header' structure follows. */
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/* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ */
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#define SG_MAX_SENSE 16 /* this only applies to the sg_header interface */
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struct sg_header
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{
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int pack_len; /* [o] reply_len (ie useless), ignored as input */
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int reply_len; /* [i] max length of expected reply (inc. sg_header) */
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int pack_id; /* [io] id number of packet (use ints >= 0) */
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int result; /* [o] 0==ok, else (+ve) Unix errno (best ignored) */
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unsigned int twelve_byte:1;
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/* [i] Force 12 byte command length for group 6 & 7 commands */
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unsigned int target_status:5; /* [o] scsi status from target */
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unsigned int host_status:8; /* [o] host status (see "DID" codes) */
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unsigned int driver_status:8; /* [o] driver status+suggestion */
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unsigned int other_flags:10; /* unused */
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unsigned char sense_buffer[SG_MAX_SENSE]; /* [o] Output in 3 cases:
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when target_status is CHECK_CONDITION or
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when target_status is COMMAND_TERMINATED or
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when (driver_status & DRIVER_SENSE) is true. */
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}; /* This structure is 36 bytes long on i386 */
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/* IOCTLs: The following are not required (or ignored) when the sg_io_hdr_t
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interface is used. They are kept for backward compatibility with
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the original and version 2 drivers. */
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#define SG_SET_TIMEOUT 0x2201 /* unit: jiffies (10ms on i386) */
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#define SG_GET_TIMEOUT 0x2202 /* yield timeout as _return_ value */
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/* Get/set command queuing state per fd (default is SG_DEF_COMMAND_Q.
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Each time a sg_io_hdr_t object is seen on this file descriptor, this
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command queuing flag is set on (overriding the previous setting). */
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#define SG_GET_COMMAND_Q 0x2270 /* Yields 0 (queuing off) or 1 (on) */
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#define SG_SET_COMMAND_Q 0x2271 /* Change queuing state with 0 or 1 */
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/* Turn on/off error sense trace (1 and 0 respectively, default is off).
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Try using: "# cat /proc/scsi/sg/debug" instead in the v3 driver */
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#define SG_SET_DEBUG 0x227e /* 0 -> turn off debug */
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#define SG_NEXT_CMD_LEN 0x2283 /* override SCSI command length with given
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number on the next write() on this file descriptor */
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/* Defaults, commented if they differ from original sg driver */
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#ifdef __KERNEL__
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#define SG_DEFAULT_TIMEOUT_USER (60*USER_HZ) /* HZ == 'jiffies in 1 second' */
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#else
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#define SG_DEFAULT_TIMEOUT (60*HZ) /* HZ == 'jiffies in 1 second' */
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#endif
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#define SG_DEF_COMMAND_Q 0 /* command queuing is always on when
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the new interface is used */
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#define SG_DEF_UNDERRUN_FLAG 0
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#endif
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