[Qemu-devel] Problem with SCSI emulation

[Qemu-devel] Problem with SCSI emulation

[Henrik Holst]

There seams to be a problem with the SCSI emulation in qemu. I
originally tripped over this using KVM but have since confirmed the
same behavior in qemu-trunk.

I have also tested on both an debian amd64 host and an ubuntu i386
host with the very same results.

Trying to install OpenBSD 4.3 as:
  qemu -drive file=test.img,if=scsi,media=disk -cdrom install43.iso -m
256 -boot d

yields continous lines of "lsi_scsi: error: Reselect with pending DMA"
from qemu and the OpenBSD installer complaints about problems to
write. I have tested with both the i386 and amd64 version of OpenBSD
with the very same problem.

If booting a linux guest such as ubuntu 8.04 the SCSI emulation seams
to work just fine until one starts qemu with -m 4096 (or higher), if
one does so the guest sees either a 512B sized drive or a drive
without a partition table (and fdisk fails to write a new partition
table in the guest).

The test.img is a 10G qcow2 file.

Since there is no direct speed difference between the ide and scsi
emulations (according to my small bonnie+++ tests) this would not
normally be a problem, but since the ide emulation is locked to a
maximum of 4 devices and we happen to have to use 5 devices :(...

I will try to go through the code my self, but would appreciate if any
one would have any ideas to what this might be due to (since I am
completely new to scsi emulation).

Sincerely, Henrik Holst