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Re: [Qemu-devel] -fda fat:dir -snapshot
From: |
Michael Tokarev |
Subject: |
Re: [Qemu-devel] -fda fat:dir -snapshot |
Date: |
Mon, 15 Mar 2010 17:20:10 +0300 |
User-agent: |
Mozilla-Thunderbird 2.0.0.22 (X11/20090706) |
Kevin Wolf wrote:
> Am 13.03.2010 20:18, schrieb Michael Tokarev:
>> Apparently this does not work, and for a loooong time:
>>
>> $ kvm -fda fat:dir
>> [ it opens the sdl window ]
>> $ kvm -fda fat:dir -snapshot
>> qemu: could not open disk image fat:dir: No such file or directory
>>
>> Is it supposed to work?
>
> Wow, that's a crazy case. I guess nobody has ever tested this, and
> indeed it looks like it never has worked. As you might know, -snapshot
> internally creates a temporary qcow2 image which takes the image you
> originally asked for as a backing file.
Yeah, I looked at strace output at least.
[]
> We could just disable this for protocols as a quick fix, but I think in
> fact you do want to have this behaviour when using protocols as a
> backing file for a persistent COW image. I guess this needs some more
> thought, especially in respect to the discussions of making
> file/host_device/... protocols.
>
> If you really have a use case for this, you can use an absolute path
> after fat: as a workaround, it won't touch the path then.
Initially it was a bugreport against kvm in Debian - see
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=504049
"Virtual FAT drive doesn't work with -snapshot", I'm not
really sure what use case there is. But for me, I already
had a more-or-less valid use case - trying a new driver in
windows, supplying it in a virtual floppy (hence fat:dir)
and checking if it works (hence -snapshot). I actually
tried to do something in the past, but didn't know the fat:
thing (apparently it is not mentioned in the manpage).
But the whole thing indeed looks somewhat.. messy. ;)
Thanks!
/mjt