On Wed, 21 Mar 2001, Bradley Broom wrote:
> Summary: My system freezes *completely* when doing an INQUIRY under 2.4.x
> kernels. SCSI card is a Tekram DC390. Only inquiries to the DISK device cause a
> hang, others succeed.
This appears to have something to do with tagged queueing on the disk drive.
If I disable tagged queueing for the disk, everything works fine. Note that
tagged queueing for the disk works ok when I mount the disk as a filesystem.
However, both cdrecord and scanbus hang when writing an INQUIRY to /dev/sg0
(the scsi device corresponding to the disk). The system freezes either while
writing the INQUIRY command or *very* shortly thereafter. The test program I
wrote never gets so far as to issue the corresponding read.
Obviously, the INQUIRY works when performed by the driver itself; it's just the
issueing of them via the SG driver that causes problems. I note that the driver
uses a special subroutine for issueing the INQUIRY command, and this routine
disables tagged queueing in the DCB. This routine isn't called when the INQUIRY
command is sent from userland via the SG driver.
Regards,
Bradley
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