NAME¶
sg_modes - reads mode pages with SCSI MODE SENSE command
SYNOPSIS¶
sg_modes [
--all] [
--control=PC] [
--dbd]
[
--dbout] [
--examine] [
--flexible] [
--help]
[
--hex] [
--list] [
--llbaa] [
--maxlen=LEN] [
--page=PG[,SPG]] [
--raw] [
-R] [
--six] [
--verbose] [
--version] [
DEVICE]
sg_modes [
-6] [
-a] [
-A] [
-c=PC] [
-d]
[
-D] [
-e] [
-f] [
-h] [
-H] [
-l]
[
-L] [
-m=LEN] [
-p=PG[,SPG]] [
-r]
[
-subp=SPG] [
-v] [
-V] [
-?] [
DEVICE]
DESCRIPTION¶
This utility sends a MODE SENSE SCSI command to the
DEVICE and outputs
the response. There is a 6 byte and 10 byte (cdb) variant of the MODE SENSE
command, this utility defaults to the 10 byte variant.
This utility decodes mode page headers and block descriptors but outputs the
contents of each mode page in hex. It also has no facility to change the mode
page contents or block descriptor data. Mode page contents are decoded and can
be changed by the
sdparm utility.
This utility supports two command line syntaxes, the preferred one is shown
first in the synopsis and explained in this section. A later section on the
old command line syntax outlines the second group of options.
If no page is given (and
--list is not selected) then
--all is
assumed. The
--all option requests all mode pages (but not subpages) in
a single response.
OPTIONS¶
Arguments to long options are mandatory for short options as well.
- -a, --all
- output all the mode pages reported by the DEVICE.
This is what the page code 63 (0x3f) is defined to do. When used once,
mode subpages are not fetched. When used twice (e.g. '-aa'), all mode
pages and subpages are requested which is equivalent to
'--page=63,255'.
- -c, --control=PC
- PC is the page control value. Up to four different
versions of each page are held by the device:
0 : current values (i.e. those active at present)
1 : changeable values
2 : default values (i.e. the manufacturer's settings)
3 : saved values
The changeable values are bit masks showing which fields could be changed
with a MODE SELECT. The saved values will be re-instated the next time the
device is power cycled or reset. If this option is not given then current
values [0] are assumed.
- -d, --dbd
- disable block descriptors. By default, block descriptors
(usually one (for disks) or none) are returned in a MODE SENSE response.
This option sets the "disable block descriptors" (DBD) bit in
the cdb which instructs the device not to return any block descriptors in
its response. Older devices may not support this setting and may return an
"illegal request" sense key; alternatively they may ignore it.
Oddly the Reduced Block Command set (RBC) requires this bit set.
- -D, --dbout
- disable outputting block descriptors. Irrespective of
whether block descriptors are present in the response or not, they are not
output.
- -e, --examine
- examine each mode page in the range 0 through to 62
(inclusive). If some response is given then print out the mode page name
or number (in hex) if the name is not known.
- -f, --flexible
- Some devices, bridges and/or drivers attempt crude
translations between MODE SENSE 6 and 10 byte commands without correcting
the response. This will cause the response to be mis-interpreted (usually
with an error saying the response is malformed). With this option, the
length of the response is checked, and if it looks wrong, the response is
then decoded as if the other mode sense (cdb length) was sent.
- -h, --help
- print out the usage message then exit.
- -H, --hex
- The default action is to decode known mode page numbers
(and subpage numbers) into text. When this option is used once, the
response is output in hexadecimal. When this option is used twice, mode
page numbers and page control values are output in hex.
- -l, --list
- lists all common page and subpage codes and their names
that are found in the command set that matches the peripheral type of the
given DEVICE. If no DEVICE and no --page=PG is given
then the common page and subpage codes and their names are listed for SBC
(e.g. a disk). If no DEVICE is given and a --page=PG is
given then the common page and subpage codes and their names are listed
for the command set whose peripheral device type matches the value given
to PG. For example 'sg_mode --list --page=1' lists the command mode
pages and subpages for tape devices. Additionally if a sub_page_code is
given then it is interpreted as a transport identifier and command
transport specific mode page codes and their names are listed following
the main mode page list. Other options are ignored.
- -L, --llbaa
- set the Long LBA Accepted (LLBAA) bit in the MODE SENSE
(10) cdb. This bit is not defined in the MODE SENSE (6) cdb so setting the
'-L' and '--six' options is reported as an error. When set the
DEVICE may respond with 16 byte block descriptors as indicated by
the 'LongLBA' field in the response. In most cases setting this option is
not needed.
- -m, --maxlen=LEN
- The LEN argument is the maximum response length in
bytes. It is the 'allocation length' field in the cdb. When not given (or
LEN is zero) then the allocation length field is set to 4096 for
MODE SENSE (10) or 252 for MODE SENSE (6). The LEN argument must be
non-negative and no greater than 65535 for MODE SENSE (10) and not greater
than 255 for MODE SENSE (6).
- -O, --old
- switch to older style options.
- -p, --page=PG
- page code to fetch. The PG is assumed to be a
decimal value unless prefixed by '0x' or has a trailing 'h'. It should be
a value between 0 and 63 (inclusive). When not given and a default is
required then a value of 63 (0x3f), which fetches all mode pages, is
used.
- -p, --page=PG,SPG
- page code and subpage code values to fetch. Both arguments
are assumed to be decimal unless flagged as hexadecimal. The page code
should be between 0 and 63 inclusive. The subpage code should be between 0
and 255 inclusive. The default value for the subpage code is 0.
- -r, --raw
- output the response in binary to stdout. Error messages and
warnings, if any, are sent to stderr. When this option is used twice (e.g.
'-rr') then has the same action as '-R'
- -R
- output the selected mode page to stdout a byte per line.
Each line contains two hexadecimal digits (e.g. "3e"). Useful as
input (after editing) to the sg_wr_mode(8) utility.
- -6, --six
- by default this utility sends a 10 byte MODE SENSE command
to the DEVICE. However some SCSI devices only support 6 byte MODE
SENSE commands (e.g. SCSI-2 tape drives). This parameter forces the use of
6 byte MODE SENSE commands.
- -v, --verbose
- increase level of verbosity. Can be used multiple
times.
- -V, --version
- print out version string then exit.
NOTES¶
If the normal sg_modes utility fails with "illegal command operation
code" then try the '--six' (or '-6') option.
This utility performs a SCSI INQUIRY command to determine the peripheral type of
the device (e.g. 0 -> Direct Access Device (disk)) prior to sending a MODE
SENSE command. This helps in decoding the block descriptor and mode pages.
In the 2.4 series of Linux kernels the
DEVICE must be a SCSI generic (sg)
device. In the 2.6 series block devices (e.g. SCSI disks and DVD drives) can
also be specified. For example "sg_modes -a /dev/sda" will work in
the 2.6 series kernels.
EXIT STATUS¶
The exit status of sg_modes is 0 when it is successful. Otherwise see the
sg3_utils(8) man page.
OLDER COMMAND LINE OPTIONS¶
The options in this section were the only ones available prior to sg3_utils
version 1.23 . In sg3_utils version 1.23 and later these older options can be
selected by either setting the SG3_UTILS_OLD_OPTS environment variable or
using '--old' (or '-O) as the first option.
- -6
- by default this utility sends a 10 byte MODE SENSE command
to the DEVICE. This parameter forces the use of 6 byte MODE SENSE
commands. See --six in the main description.
- -a
- see --all in the main description.
- -A
- output all the mode pages and subpages supported by the
DEVICE. Same as '--all --all' in the new syntax.
- -c=PC
- PC is the page control value. See
--control=PC in the main description.
- -d
- see --dbd in the main description.
- -D
- see --dbout in the main description.
- -e
- see --examine in the main description.
- -f
- see --flexible in the main description.
- -h
- The default action is to decode known mode page numbers
(and subpage numbers) into text. With this option mode page numbers (and
subpage numbers) are output in hexadecimal.
- -H
- same action as the '-h' option.
- -l
- see --list in the main description.
- -L
- see --llbaa in the main description.
- -N
- switch to the newer style options.
- -m=LEN
- see --maxlen=LEN in the main
description.
- -p=PG
- PG is page code to fetch. Should be a hexadecimal
number between 0 and 3f inclusive (0 to 63 decimal). The default value
when required is 3f (fetch all mode pages).
- -p=PG,SPG
- page code and subpage code values to fetch. The page code
should be a hexadecimal number between 0 and 3f inclusive. The subpage
code should be a hexadecimal number between 0 and ff inclusive. The
default value for the subpage code is 0.
- -r
- output the selected mode page to stdout a byte per line.
Each line contains two hexadecimal digits (e.g. "3e"). Useful as
input (after editing) to the sg_wr_mode(8) utility.
- -subp=SPG
- sub page code to fetch. Should be a hexadecimal number
between 0 and 0xff inclusive. The default value is 0.
- -v
- increase verbosity of output.
- -V
- print out version string then exit.
- -?
- output usage message then exit. Ignore all other
parameters.
AUTHOR¶
Written by Doug Gilbert
REPORTING BUGS¶
Report bugs to <dgilbert at interlog dot com>.
COPYRIGHT¶
Copyright © 2000-2008 Douglas Gilbert
This software is distributed under the GPL version 2. There is NO warranty; not
even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO¶
sdparm(8), sg_wr_mode(8), sginfo(8), sgmode(scsirastools),
scsiinfo(net), scu(net), seatools(seagate)
All these utilities offer some facility to change mode page (or block
descriptor) parameters.