[518] in linux-scsi channel archive
Selectable Generic SCSI
daemon@ATHENA.MIT.EDU (Brit Systems)
Wed Aug 16 22:33:57 1995
Date: Wed, 16 Aug 1995 13:07:40 -0500 (CDT)
From: Brit Systems <brit@metronet.com>
To: linux-scsi@vger.rutgers.edu
I'm playing with the generic SCSI device. Since some of the devices,
like robotic arms, are kind of slow, I wanted to use select to tell
me when the SCSI command has completed.
I tried to write a command to the sg device, then do a select on it
to wait for it to become ready to read, then I read the device.
It appears that the select will return immediately. Sometimes the read
will take a long time after that.
When I open the device with a O_NONBLOCK flag set, the select still
returns immediately but the read will fail with "Try Again". After
several retries, it eventually gets it.
I looked through the source and see that select is not implemented
in the version I have (1.2).
If it does not support it, can someone give me an idea how hard it is
to add that kind of support?
Is there some better way that I should try doing this?
Thanks,
Robbie Barton
BRIT Systems, Medical Imaging
3626 N. Hall Street, Suite 616, Dallas, TX 75219
(214) 528-4446 fax: (214) 528-4916
