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

[Paolo Bonzini <pbonzini@redhat.com>]

On 11/02/2011 04:15 PM, Thomas Schmitt wrote:
> Hi,
>
> Stefan Hajnoczi wrote:
>> I actually suggest focussing just
>> on qemu.git/master because that is where developers mostly invest
>> their time.
>
> I did now
>    git clone git://git.qemu.org/qemu.git
>    cd qemu&&  ./configure&&  make
>
> I assume this binary is the right one for my "AMD Athlon(tm) II X4 620"
>    ./x86_64-softmmu/qemu-system-x86_64
> Together with
>    -L ...absolute.path.../pc-bios
> it still complains on startup
>    Could not open option rom 'sgabios.bin': No such file or directory
>
> I cannot spot a file sgabios.bin on the entire host machine by
>    find / -name sgabios.bin 2>/dev/null
>
> I repeated the experiments as on qemu-0.15.1. Same results.
>
> If i shall do any further experiments, please give me direct
> instructions. (I'm not much accustomed to qemu and git. Assume
> that i know nothing beyond what i show here.)

This is a packaging bug, I think.  Will look at it tomorrow.

> Drive list as detected by xorriso:
>    0  -dev '/dev/sr0' rwrw-- :  'TSSTcorp' 'CDDVDW SH-S223B'
>    1  -dev '/dev/sr1' rwrw-- :  'QEMU    ' 'QEMU DVD-ROM'
>
> Burn attempt on CD-RW:
>    xorriso -for_backup -scsi_log on -dev /dev/sr0 -add /usr/lib --
> fails and leaves the CD-RW unchanged.
> (With CD-RW, qemu does not abort as with DVD+RW.)
>
> Undesirable SCSI transaction outcome with these commands:
>
>    PREVENT/ALLOW MEDIA REMOVAL
>    1e 00 00 00 01 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)
>
>    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)
>
>    SET CD SPEED
>    bb 00 ff ff 06 e4 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)
>
>    WRITE(10)
>    2a 00 00 00 99 0f 00 00 10 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   (     4 ms)
> (This tried to send 32 kB of data to block 39183 decimal, where the
>   new track has to start.)
>
>    SYNCHRONIZE CACHE
>    35 02 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)
>
>    CLOSE TRACK/SESSION
>    5b 01 02 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)
>
> The sense code is listed in MMC as:
>    B 00 06 I/O PROCESS TERMINATED

Is it good or bad? :)  I see it even in the very first command.

> The attempt to learn about the medium causes two timeouts after 200
> seconds each. (I should reduce the time for these experiments.)
>    xorriso -scsi_log on -dev /dev/sr0 -toc
>
> has timeouts with
>    READ DISC STRUCTURE
>    ad 00 00 00 00 00 00 04 00 04 00 00
> and
>    READ DISC STRUCTURE
>    ad 00 00 00 00 00 00 11 00 04 00 00

What do these give on the host?  Sounds like another LSI emulation bug.

> The current release 1.1.6 will not recognize QEMU DVD-ROM because
> of its inconsistent Mode Page 2Ah with short Page Length (18 decimal).

The page length is indeed 18 for IDE and 20 for SCSI.  I made some 
changes to that page recently, but left the 18 because I feared causing 
regression.  But if that is a bug, we can probably fix it in 1.0.

> About the non-passthrough QEMU DVD-ROM :
>
> i wrote:
>>>    -drive file=/dev/sg2,if=scsi,bus=4,unit=0,media=cdrom
>>> Now i have two drives by one option [...]
>>> 0 -dev '/dev/sr0' rwrw-- : 'TSSTcorp' 'CDDVDW SH-S223B'
>>> 1 -dev '/dev/sr1' rwrw-- : 'QEMU    ' 'QEMU DVD-ROM'
>>> with /dev/sr1 being an empty drive. (Is this a known bug ?)
>
> Stefan Hajnoczi wrote:
>> Off the top of my head I'd say this is an empty IDE CD-ROM drive which
>> is added by default.  Would need to check the code to be sure though.
>
> Actually i meant:
> Is it a known bug that 'QEMU DVD-ROM' is always empty if it stems
> from option -drive if=scsi ?

No, it is not a bug.  Remember this is an IDE DVD-ROM.  It is not 
instantiated by -drive if=scsi: it is the same device that -cdrom 
crsates, only empty because you didn't specify any medium.  You can open 
the tray, close the tray, change the medium with the monitor.

> The fact that 'QEMU DVD-ROM' from file=/dev/sg2,if=scsi behaves like
> the drives from the other file=...,if=scsi makes me think that it is
> an emulated SCSI drive.

It is not, try inspecting /dev/disk and sysfs.  The ATAPI and SCSI code 
is indeed very similar and will be even more similar in 1.0, but for now 
they are distinct.

Paolo