Re: [Qemu-devel] [PATCH 05/18] ide: Turn debug messages into assertions

[Kevin Wolf]

Am 01.06.2011 15:44, schrieb Luiz Capitulino:
> On Thu, 26 May 2011 18:12:08 -0300
> Luiz Capitulino <address@hidden> wrote:
> 
>> On Thu, 19 May 2011 14:33:19 +0200
>> Kevin Wolf <address@hidden> wrote:
>>
>>> These printfs aren't really debug messages, but clearly indicate a bug if 
>>> they
>>> ever become effective.
>>
>> Then we have a bug somewhere, starting a VM with:
>>
>>  # qemu -hda disks/test.img -enable-kvm -m 1G -cdrom /dev/sr0
>>
>> Where the host's CDROM is empty, triggers one of these asserts:
>>
>>  qmp-unstable/hw/ide/pci.c:299: bmdma_cmd_writeb: Assertion 
>> `bm->bus->dma->aiocb == ((void *)0)'
> 
> I found out why this is happening. I'm passing '-snapshot' to the 
> command-line,
> sorry for not mentioning it (I forgot I was using my devel alias).

And suddenly it's reproducible. :-)

I'll have a look.

> I also found out that /usr/bin/eject in the guest won't work when
> -snapshot is used. Shouldn't qemu ignore this flag when using cdrom
> passthrough?

"Won't work" means that it works like with a CD-ROM image? That would be
what I expect, as you end up having a qcow2 image with -snapshot.

Not sure what's the best way of fixing this. Maybe just ignoring
-snapshot for read-only block devices? Or we could try and forward the
eject request to the backing file if the format driver doesn't handle it.

Kevin