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

[Thomas Schmitt]

Hi,

Paolo Bonzini wrote:
> I suggest trying with 1.0-rc (origin/master).

Am i on the right track with  git clone git://git.qemu.org/qemu.git  ?


> scsi-block uses
> read+write for READ/WRITE CDBs and SG_IO for everything else.

That sounds scary to me. On real Linux systems it is not advisable to
mix SG_IO and block device driver. At least not with optical media.
Often the block device does not learn about status changes until
the tray gets ejected and reloaded manually or by the block device
driver. If i load it by START/STOP UNIT via SG_IO, then the block
device driver believes there are no readable blocks on the medium.

Shall i really try this ?

In my experiments WRITE(10) did fail. But so did other commands.
Critical is most probably the failure of
  MODE SELECT
  55 10 00 00 00 00 00 00 3c 00 
  To drive: 60b
  00 00 00 00 00 00 00 00 05 32 01 00 00 00 00 00 00 00 00 00
  00 00 00 96 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  +++ sense data = F0 00 0B 00 00 00 00 0A 00 00 00 00 00 06 00 00 00 00
  +++ key=B  asc=00h  ascq=06h   (     0 ms)
which shall announce the CD write parameters to the drive (Mode Page 5).
Without it, you have no control and depend on the existence of a
suitable default.

Actually i cannot spot in my experiments a single successful command
with transfer direction to the drive.
READ(10), on the other hand, works well.


Have a nice day :)

Thomas