cvs commit: src/sys/cam/scsi scsi_sg.c scsi_sg.h src/sys/modules/cam Makefile src/sys/conf NOTES files src/sys/compat/linux linux_ioctl.c linux_ioctl.h

[Scott Long]

To tell you the truth, the SG device has one of the worst programming 
interfaces that I've ever seen.  Even the various official docs on it
complain about how bad it is.  I've written apps for CAM, including a
swiss-army-knife java-based management app, and CAM is vastly superior.
I tried porting the app to linux and gave up due to how limited and
unpleasant it was.  From the kernel side, it's even scarier.

But beyond that, the work I committed here was about opening up FreeBSD
to more storage management opportunities.  So I'm happy with whatever
anyone wants to do with it that furthers that goal.  I'd like to see
the native interface be used as a bridge to help introduce programmers
to FreeBSD and CAM; if the sg3_utils package is a step in that
direction or if it provides tools that camcontrol doesn't, then go for
it.

Scott


mjacob at freebsd.org wrote:
> 
> Cool- does this mean we should commit sg3_utils to ports then?
> 
> On Sat, 7 Apr 2007, Scott Long wrote:
> 
>> scottl      2007-04-07 19:40:58 UTC
>>
>>  FreeBSD src repository
>>
>>  Modified files:
>>    sys/modules/cam      Makefile
>>    sys/conf             files NOTES
>>    sys/compat/linux     linux_ioctl.c linux_ioctl.h
>>  Added files:
>>    sys/cam/scsi         scsi_sg.c scsi_sg.h
>>  Log:
>>  Add the CAM 'SG' peripheral device.  This device implements a subset 
>> of the
>>  Linux SCSI SG passthrough device API.  The intention is to allow for 
>> both
>>  running of Linux apps that want to talk to /dev/sg* nodes, and to 
>> facilitate
>>  porting of apps from Linux to FreeBSD.  As such, both native and 
>> linuxolator
>>  entry points and definitions are provided.
>>
>>  Caveats:
>>   - This does not support the procfs and sysfs nodes that the Linux SG
>>     driver provides.  Some Linux apps may rely on these for operation,
>>     others may only use them for informational purposes.
>>   - More ioctls need to be implemented.
>>   - Linux uses a naming scheme of "sg[a-z]" for devices, while FreeBSD 
>> uses a
>>     scheme of "sg[0-9]".  Devfs aliasis (symlinks) are automatically 
>> created
>>     to link the two together.  However, tools like camcontrol only see 
>> the
>>     native names.
>>   - Some operations were originally designed to return byte counts or 
>> other
>>     data directly as the syscall return value.  The linuxolator 
>> doesn't appear
>>     to support this well, so this driver just punts for these cases.
>>
>>  Now that the driver is in place, others are welcome to add missing
>>  functionality.  Thanks to Roman Divacky for pushing this work along.
>>
>>  Revision  Changes    Path
>>  1.1       +987 -0    src/sys/cam/scsi/scsi_sg.c (new)
>>  1.1       +139 -0    src/sys/cam/scsi/scsi_sg.h (new)
>>  1.138     +27 -0     src/sys/compat/linux/linux_ioctl.c
>>  1.25      +34 -0     src/sys/compat/linux/linux_ioctl.h
>>  1.1419    +5 -0      src/sys/conf/NOTES
>>  1.1191    +1 -0      src/sys/conf/files
>>  1.15      +1 -0      src/sys/modules/cam/Makefile
>>