.git/config corruption using 9p virtio in guest

.git/config corruption using 9p virtio in guest

[Darren Hart]

I have a 32b Fedora 15 guest mounting a filesystem from an Ubuntu 11.10
64b host using virtio and 9p. I'm using the "mapping" security mode
(tried squash as well). While I can create, edit, and delete files, when
I try to create or clone a git repository, I end up with garbage for the
first bit of the newly created .git config.

$ kvm --version
QEMU emulator version 0.14.1 (qemu-kvm-0.14.1), Copyright (c) 2003-2008
Fabrice Bellard

$ uname -a
Linux rage 3.0.0-12-server #20-Ubuntu SMP Fri Oct 7 16:36:30 UTC 2011
x86_64 x86_64 x86_64 GNU/Linux

$ virt-manager --version
Gtk-Message: Failed to load module "pk-gtk-module"
Gtk-Message: Failed to load module "canberra-gtk-module"
0.9.0

The underlying filesystem on the host is an md RAID0 array mounted as:
/dev/md0 on /build type ext4 (rw,noatime,nodiratime,commit=6000)

I was hoping to use 9p/virtio to avoid having to generate a number of
larger vm images which I'm using to build full OSes. I'd like the
resulting images to be easily accessible on the host.

Any thoughts on a solution?

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel

Re: .git/config corruption using 9p virtio in guest

[Stefan Hajnoczi]

On Sat, Nov 5, 2011 at 12:52 AM, Darren Hart <dvhart@linux.intel.com> wrote:
> I have a 32b Fedora 15 guest mounting a filesystem from an Ubuntu 11.10
> 64b host using virtio and 9p. I'm using the "mapping" security mode
> (tried squash as well). While I can create, edit, and delete files, when
> I try to create or clone a git repository, I end up with garbage for the
> first bit of the newly created .git config.
>
> $ kvm --version
> QEMU emulator version 0.14.1 (qemu-kvm-0.14.1), Copyright (c) 2003-2008
> Fabrice Bellard
>
> $ uname -a
> Linux rage 3.0.0-12-server #20-Ubuntu SMP Fri Oct 7 16:36:30 UTC 2011
> x86_64 x86_64 x86_64 GNU/Linux
>
> $ virt-manager --version
> Gtk-Message: Failed to load module "pk-gtk-module"
> Gtk-Message: Failed to load module "canberra-gtk-module"
> 0.9.0
>
> The underlying filesystem on the host is an md RAID0 array mounted as:
> /dev/md0 on /build type ext4 (rw,noatime,nodiratime,commit=6000)
>
> I was hoping to use 9p/virtio to avoid having to generate a number of
> larger vm images which I'm using to build full OSes. I'd like the
> resulting images to be easily accessible on the host.
>
> Any thoughts on a solution?

Can you describe the corrupted .git/config in more detail?

Does git give you an error message?

Can you hexdump or post the file contents - often corrupted files
contain a clue as to how the corruption occurred?

CCed Aneesh, QEMU virtfs maintainer.

Stefan