Re: [Qemu-devel] Playing with virtfs.

["Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>]

On Sun, 23 Jan 2011 13:33:14 -0600, Rob Landley <rob@landley.net> wrote:
> Using yesterday's -git, following the instructions in
> http://wiki.qemu.org/Documentation/9psetup (which is missing a kernel
> symbol, you need to add CONFIG_VIRTIO_PCI to your kernel too), I managed
> to mount a read-only virtfs filesystem, adding this to the
> qemu-system-x86_64 command line:

With top of the kernel tree 52cfd503ad7176d23a5dd7af3981744feb60622f
I am able to build the kernel without CONFIG_VIRTIO_PCI. What is the
exact error you are finding ?

> 
> -virtfs
> local,security_model=passthrough,mount_tag=kvm,path=/home/landley/9ptest
> 
> And then in the emulated Linux:
> 
>   root@kvm:~# mount -t 9p -o trans=virtio,version=9p2000.L kvm woot
>   root@kvm:~# ls -l woot
>   total 80
>   -rw-r--r-- 1 1000 1000 77874 Jan 22 23:33 config-linux
>   root@kvm:~# cd woot
>   root@kvm:~/woot# touch fred
>   touch: setting times of `fred': No such file or directory
>   root@kvm:~/woot#
> 
> I.E. It seems to work fine read only, but changes are discarded.
> 
> Am I doing something wrong, or is this expected?  (If so, when is write
> support likely to go in?)
> 

Are you running qemu as root ? Using passthrough security model require
the ability to change the ownership of the file. Otherwise you can use
security=none, but the credentials with which files are created will
not be correct. 

-aneesh