README.freebsd

Introduction
============
The FreeBSD port of sg3_utils contains those utilities that are _not_
specific to Linux. In some cases the FreeBSD camcontrol command supplies
similar functionality; for example 'sg_map' is similar to
'camcontrol devlist'.

The dd variants from the sg3_utils package (e.g. sg_dd) rely on too many
Linux idiosyncrasies to be easily ported. A new package called 'ddpt'
contains a utility with similar functionality to sg_dd and ddpt is available
for FreeBSD.

Supported Utilities
===================
Here is a list of utilities that have been ported:
    sg_bg_ctl
    sg_compare_and_write
    sg_decode_sense
    sg_format
    sg_get_config
    sg_get_elem_status
    sg_get_lba_status
    sg_ident
    sg_inq          [dropped ATA IDENTIFY DEVICE capability]
    sg_logs
    sg_luns
    sg_modes
    sg_opcodes
    sg_persist
    sg_prevent
    sg_raw
    sg_rdac
    sg_read_block_limits
    sg_read_buffer
    sg_read_long
    sg_readcap
    sg_reassign
    sg_referrals
    sg_rep_pip
    sg_rep_zones
    sg_requests
    sg_rmsn
    sg_rtpg
    sg_safte
    sg_sanitize
    sg_sat_identify
    sg_sat_phy_event
    sg_sat_set_features
    sg_seek
    sg_senddiag
    sg_ses
    sg_start
    sg_stpg
    sg_stream_ctl
    sg_sync
    sg_turs
    sg_verify
    sg_unmap
    sg_vpd
    sg_wr_mode
    sg_write_buffer
    sg_write_long
    sg_write_same
    sg_write_verify
    sg_write_x
    sg_zone

Most utility names are indicative of the main SCSI command
that they execute.  Some utilities are slightly higher level, for
example sg_ses fetches SCSI Enclosure Services (SES) status pages and
can send control pages. Each utility has a man page (placed in
section 8). An overview of sg3_utils can be found at:
https://sg.danny.cz/sg/sg3_utils.html .
A copy of the "sg3_utils.html" file is in the "doc" subdirectory.


The executables and library can be built from the source code in
the tarball and installed with the familiar
"./configure ; make ; make install" sequence. If this fails try
running the "./autogen.sh" script prior to that sequence. There
are generic instruction on configure and friend in the INSTALL file.

Some man pages have examples which use Linux device names which
hopefully will not confuse the FreeBSD users.

Device naming
=============
In FreeBSD disks have block names like '/dev/da0' with a corresponding
pass-through device name like '/dev/pass0'. Use this command:
"camcontrol devlist" to see that SCSI devices available. To list NVMe
devices: "nvmecontrol devlist" can be used. Any many, but not all
contexts, the device name can be used without the '/dev/' prefix.
FreeBSD is relatively unique in this respect and support for this
abbreviated form has been broken in this package and fixed in
sg3_utils release 1.46 .

Device naming for NVMe is a bit more complex. Controllers have names
like /dev/nvme0 and namespaces /dev/nvme0ns1 . Partitions are not
supported on /dev/nvme0ns1 type nodes. Instead there are /dev/nvd0
and /dev/nvd0p<m> where <m> is th partition number starting at 1.
The nvd driver (written by Intel) is not CAM compatible and has its
own utility nvmecontrol which has similar capabilities as camcontrol
has for CAM devices. In FreeBSD release 12 the nda driver was
introduced with names like /dev/nda0 and /dev/nda0n<m>. The difference
is that nda is CAM compatible. From the point of view of this package,
the nda driver is preferred as CAM supports NVMe command timeouts and
the error processing is more mature. 

FreeBSD installation
====================
The traditional './configure ; make ; make install' sequence from the
top level of the unpacked tarball will work on FreeBSD. But the man pages
will be placed under the /usr/local/share/man directory which unfortunately
is not on the standard manpath. One solution is to add this path by
creating a file with a name like local_share.conf in the
/usr/local/etc/man.d/ directory and placing this line in it:
    MANPATH /usr/local/share/man

FreeBSD 9.0 has a "ports" entry for sg3_utils under the
/usr/ports/sysutils directory. It points to version 1.28 of sg3_utils
which is now a bit dated. It could be used as a template to point
to more recent versions.

kFreeBSD
========
sg3_utils can be built into a Debian package for kFreeBSD using the
./build_debian.sh script in the top level directory. This has been tested
with Debian 6.0 release.

Details
=======
Most of the ported utilities listed above use SCSI command functions
declared in sg_cmds_*.h headers . Those SCSI command functions are
implemented in the corresponding ".c" files. The ".c" files pass SCSI
commands to the host operating system via an interface declared in sg_pt.h .
There are currently five implementations of that interface depending on
the host operating system:
  - sg_pt_linux.c
  - sg_pt_freebsd.c
  - sg_pt_osf1.c  [Tru64]
  - sg_pt_win32.c
  - sg_pt_solaris.c

The sg_pt_freebsd.c file uses the FreeBSD CAM SCSI pass through mechanism.
Hence only FreeBSD device nodes that support CAM can be used. These can be
viewed with the "camcontrol devlist" command. To access ATAPI devices (e.g.
ATAPI DVD drives) the kernel may need to be configured with the "atapicam"
device.

Attempts to send SCSI commands with data-in or data-out buffers around 64 KB
and larger failed on a FreeBSD 7.0 with an "argument list too long" error
message. There is an associated kernel message (viewable with dmesg) that an
attempt has been made to map <n> bytes which is greater than
DFLTPHYS(65536). Still a problem in FreeBSD 8.1 . Due to CAM overhead the
largest power of 2 that can fit through with one command is 32768 bytes (32
KB).

FreeBSD 9.0 is the most recent version of FreeBSD tested with these
utilities.



Douglas Gilbert
1st May 2021