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README
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README
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For a description of this utility see:
https://sg.danny.cz/scsi/lsscsi.html
or
https://doug-gilbert.github.io/scsi/lsscsi.html
Here is a summary:
lsscsi
------
The lsscsi utility lists information about SCSI devices in Linux. Using SCSI
terminology, lsscsi lists SCSI logical units (or SCSI targets when the
'--transport' option is given). The default action is to produce one line of
output for each SCSI device currently attached to the system. In version 0.30
of this utility, support was added to list NVMe namespaces (under SCSI
devices(LUs)) and NVMe controllers (under SCSI hosts).
Note that ATA/SATA devices and USB Mass Storage (and UAPS) devices use the
SCSI subsystem in Linux thus also appear in lsscsi output.
By default its output is plain text (ASCII). With the --json option it can
produce JSON output instead.
lsscsi overlaps with the lsblk utility but concentrates on the devices
themselves. Also lsscsi lists storage related devices such as enclosures
and tape drives.
The "man" page (lsscsi.8) in this package may also be useful.
ls_name_value
-------------
The ls_name_value script (bash rather than C binary) is designed to show
filenames and their corresponding ASCII contents (values) up to two
directory levels deep. It produces plain text output.
It is designed for data-mining in the sysfs pseudo file system but may
also be useful with other pseudo file systems (e.g. devfs and procfs).
Building package
================
Installation instructions are in the INSTALL file.
Various options can be given to the ./configure script. Those
specific to this package are:
--disable-nvme-supp remove all or most NVMe code
--disable-fast-lebe use generic little-endian/big-endian code instead
--enable-debug Turn on debugging
The first option may be required for old Linux systems that pre-date
NVMe support in the kernel.
In almost all cases "fast-lebe" should be okay. The problem is that there
are two (major) ways of representing integers that require greater than 8
bits to represent. The most logical (for humans) is called "big endian"
where the high(er/est) byte appears before (i.e. at a lower address) the
low(er-est) byte. Networking and SCSI use the "big endian" representation.
Intel have always maintained that the "little endian" representation is
more computationally efficient and judging from most modern CPU designs,
the industry seems to agree with them. Some CPUs, such as those from ARM,
can run in either big or little endian mode. That said, there are few
examples of Linux or Unix using big endian ARM: Gentoo (Linux) and NetBSD
have support for big endian ARM. NVMe, a project started by Intel, uses
little endian (but not exclusively as some unique identifiers specify big
endian (e.g. IEEE NAA)). So its a mess, that won't be sorted any time soon.
There is another, more subtle issue, associated with the alignment of the
integer representation in memory that is best addressed at the same time
as "endian-ness". Along the "wire" (transport medium) it is often best to
pack integers so there are no fill characters (bytes) between them. If
the --disable-fast-lebe is needed, then probably there will be other
serious issues.
The build sequence is now:
./autogen.sh ; ./configure ; make ; make install
or
./bootstrap ; ./configure ; make ; make install
Note that the final 'make install' will usually require root permissions
and will place binaries in the /usr/local/bin directory.
Douglas Gilbert
30th May 2023