aboutsummaryrefslogtreecommitdiffstats
path: root/include
diff options
context:
space:
mode:
Diffstat (limited to 'include')
-rw-r--r--include/scsi/sg.h91
1 files changed, 24 insertions, 67 deletions
diff --git a/include/scsi/sg.h b/include/scsi/sg.h
index a9f3c6fc3f57..d8c0c4307fca 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 */

Privacy Policy