Re: [Qemu-devel] Do you have a use for a tester of virtio-scsi with CD drives ?

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Paolo Bonzini wrote:
> Can you retry this running qemu as root or with CAP_SYS_RAWIO?

No improvement to see.

On a new DVD+RW i do

  $ xorriso -for_backup -scsi_log on -dev /dev/sr1 -add /usr/include --

and still get

  FORMAT UNIT
  04 11 00 00 00 00 
  To drive: 12b
  00 02 00 08 ff ff ff ff 98 00 00 00 
  +++ sense data = F0 00 0B 00 00 00 00 0A 00 00 00 00 00 00 00 00 00 00
  +++ key=B  asc=00h  ascq=00h   (   484 ms)

The same with an attempt to reformat an already formatted DVD+RW.
  $ xorriso -scsi_log on -dev /dev/sr1 -format full

The same with a write run attempt onto a partially formatted DVD+RW.
The FORMAT UNIT command is slightly different:

  FORMAT UNIT
  04 11 00 00 00 00 
  To drive: 12b
  00 02 00 08 ff ff ff ff 98 00 00 01 
  xorriso : UPDATE : Formatting. Working since 2 seconds
  +++ sense data = F0 00 0B 00 00 00 00 0A 00 00 00 00 00 00 00 00 00 00
  +++ key=B  asc=00h  ascq=00h   (   516 ms)

The same with the attempt to format a sequential DVD-RW (details will be
part of my next report installment about DVD-RW and DVD-R).


qemu start command was:

  .../x86_64-softmmu/qemu-system-x86_64 \
     -L .../pc-bios \
     -enable-kvm \
     -nographic \
     -m 512 \
     -net nic,model=ne2k_pci \
     -net user,hostfwd=tcp::5557-:22 \
     -hda /dvdbuffer/i386-install.qemu \
     -drive file=/dev/sg2,if=scsi \
     -cdrom /dvdbuffer/pseudo_drive

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A passthrough device based on /dev/sr would increase superuser safety.

Running as superuser appears to be quite dangerous in conjunction
with Linux happiness to permutate /dev/sg numbers at boot time.
I first started it with the /dev/sg of the hard disk by mistake.
qemu was stuck at 100% CPU, and the host system did not react on
shutdown -h.
Had to press the hardware reset button. To my luck, it still booted
afterwards.

I now let cdrskin check the /dev/sg file before starting qemu.
So hopefully this will not happen again.
Nevertheless i would prefer to run qemu as normal user.

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Have a nice day :)

Thomas