Re: [Qemu-discuss] Starting qemu with virtio and .raw image file

[Supriya Kher]

Hi all,

Any inputs on this one ?

On Fri, Jul 13, 2012 at 12:10 AM, Supriya Kher <address@hidden> wrote:
> Hi,
>
> I am using qemu-system_x86_64 to create a nested virtualization setup.
> The inner guest VM is seen to be very slow. In order to improve guest
> VM performance I have been attempting to start external/outer VM using
> virtio option. However I encounter kernel crashes/failures each time.
>
> I start the outer VM running on Ubuntu using the following command
> line ( The VM image resides as a disk file of .raw format)
>
> # start qemu-kvm
>    sudo $TOOLKIT_PATH/bin/qemu-system-x86_64 -nographic \
>    -echr 20 \
>    -cpu host \
>    -m $MEMORY_SIZE \
>    -smp $NUM_VCPUS \
>    -drive file=$IMAGE_DISK,if=ide \
>    $interfaces
>
> Option 1:
>
> Changed if=ide to if=virtio
>
> sudo $TOOLKIT_PATH/bin/qemu-system-x86_64 -nographic \
>  -echr 20 \
>  -cpu host \
>  -m $MEMORY_SIZE \
>  -smp $NUM_VCPUS \
>  -drive file=$IMAGE_DISK,media=disk,if=virtio \
>   $interfaces
>
> VM crashed with the following trace:
>
> md: ... autorun DONE.
> Root-NFS: No NFS server available, giving up.
> VFS: Unable to mount root fs via NFS, trying floppy.
> VFS: Cannot open root device "sda6" or unknown-block(2,0)
> Please append a correct "root=" boot option; here are the available 
> partitions:
> VFS: Unable to mount root fs on unknown-block(2,0)
> User configuration error - no valid root filesystem found
> Kernel panic - not syncing: Invalid configuration from end user
> prevents continuing
> Pid: 1, comm: swapper Not tainted 2.6.34.10-grsec-WR4.3.0.0_cgl #1
> Call Trace:
> [<ffffffff817015d8>] ? gss_kerberos_ops+0xb9db8/0x1477e0
> [<ffffffff817015d8>] ? gss_kerberos_ops+0xb9db8/0x1477e0
> [<ffffffff815c1551>] panic+0xf5/0x16a
> [<ffffffff8161cde0>] ? vga_con+0x0/0xd0
> [<ffffffff818aa25b>] mount_block_root+0x1e3/0x1fa
> [<ffffffff818aa33c>] mount_root+0xca/0xf6
> [<ffffffff818aa4d8>] prepare_namespace+0x170/0x1a9
> [<ffffffff818a9796>] kernel_init+0x21f/0x23b
> [<ffffffff81003474>] kernel_thread_helper+0x4/0x10
> [<ffffffff815c4d55>] ? restore_args+0x0/0x30
> [<ffffffff818a9577>] ? kernel_init+0x0/0x23b
> [<ffffffff81003470>] ? kernel_thread_helper+0x0/0x10
>
>
> Option 2:
> I next tried to append "root=  as indicated in the above error
>
> sudo $TOOLKIT_PATH/bin/qemu-system-x86_64 -nographic \
>  -echr 20 \
>  -cpu host \
>  -m $MEMORY_SIZE \
>  -smp $NUM_VCPUS \
>  -drive file=$IMAGE_DISK,media=disk,if=virtio \
>  -append "root=/dev/sda1" \
>   $interfaces
>
> It appears that append option has to be accompanied with a
> corresponding "-kernel " option. VM Failed with error :
>
> -append only allowed with -kernel option
>
> Can someone help me in bringing up the VM using virtio the right way ?
>
> Thanks.
> S. K