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

[Luiz Capitulino]

On Wed, 01 Jun 2011 16:02:56 +0200
Kevin Wolf <address@hidden> wrote:

> 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.

Thanks.

> > 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?

I guess so.

> 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?

I think that makes sense as the reason to use -snapshot is to avoid
writing to the image/device.

> Or we could try and forward the
> eject request to the backing file if the format driver doesn't handle it.
> 
> Kevin
>