Re: Porting xen on rpi4

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 24 Aug 2022, Vipul Suneja wrote:
> Hi Bertrand,
> Thanks for your response!
> 
> I builded the guest image on yocto kirkstone source which has FSTYPE ext3. 
> Guest image generated is
> xen-guest-image-minimal-raspberrypi4-64.ext3.
> Below is the content of guest.cfg file
> 
>    kernel = "/home/root/Image" 
>    cmdline = "console=hvc0 earlyprintk=xen sync_console root=/dev/xvda" 
>    memory = "256" 
>    name = "guest1" 
>    vcpus = 1 
>    serial="pty" 
>    disk = [ 'phy:/dev/loop0,xvda,w' ] 
>    vif=[ 'mac=00:11:22:66:88:22,bridge=xenbr0,type=netfront', ]
> 
> I am trying to mount xen-guest-image-minimal-raspberrypi4-64.ext3 to a 
> virtual device & then will run the guest VM by command "xl create -c
> guest.cfg". But facing issue while trying to mount. 

You don't actually need to mount
xen-guest-image-minimal-raspberrypi4-64.ext3 anywhere to use it to run
your guest VM with "xl create". 

It is enough to do this instead, as Bertrand suggested:

disk=["file:/path/to/file/xen-guest-image-minimal-raspberrypi4-64.ext3,xvda,w"]

No need to call losetup or mount. Just xl create -c.

More answers below.


> Regards,
> Vipul Kumar
> 
> On Wed, Aug 24, 2022 at 8:06 PM Bertrand Marquis <Bertrand.Marquis@xxxxxxx> 
> wrote:
>       Hi Vipul,
> 
>       > On 24 Aug 2022, at 15:16, Vipul Suneja <vsuneja63@xxxxxxxxx> wrote:
>       >
>       > Hi,
>       >
>       > I am porting xen hypervisor on rpi4 with yocto kirkstone sources. 
> Followed the basic steps to build xen-image-minimal &
>       xen-guest-image-minimal. I could flash sd card with xen minimal image & 
> could see dom0 up. I copied "Image",
>       "xen-guest-image-minimal" .ext3 file & guest.cfg to "/home/root". After 
> that created a bridge with below step:
>       >
>       > killall -SIGUSR2 udhcpc
>       > brctl addbr xenbr0
>       > brctl addif xenbr0 eth0
>       > killall udhcpc
>       > udhcpc -R -b -p /var/run/udhcpc.xenbr0.pid -i xenbr0
>       >
>       > Could see the xenbr0 interface up.
>       > After that while mounting the guest file system it shows no such file 
> or directory but the file is already there.
>       >
>       > [23:40:15] <Guest9046> root@raspberrypi4-64:~# ls -l
>       > [23:40:15] <Guest9046> -rw-r--r--    1 root     root      24652288 
> Mar  9 12:36 Image
>       > [23:40:15] <Guest9046> -rw-r--r--    1 root     root           247 
> Mar  9 12:37 guest1.cfg
>       > [23:40:15] <Guest9046> -rw-r--r--    1 root     root     868220928 
> Mar  9 12:39 xen-guest-image-minimal-raspberrypi4-64.ext3
>       > [23:40:15] <Guest9046> root@raspberrypi4-64:~# chmod 0777 
> xen-guest-image-minimal-raspberrypi4-64.ext3
>       > [23:40:15] <Guest9046> root@raspberrypi4-64:~# ls -l
>       > [23:40:15] <Guest9046> -rw-r--r--    1 root     root      24652288 
> Mar  9 12:36 Image
>       > [23:40:15] <Guest9046> -rw-r--r--    1 root     root           247 
> Mar  9 12:37 guest1.cfg
>       > [23:40:15] <Guest9046> -rwxrwxrwx    1 root     root     868220928 
> Mar  9 12:39 xen-guest-image-minimal-raspberrypi4-64.ext3
>       > [23:40:15] <Guest9046> root@raspberrypi4-64:~# losetup /dev/loop0 
> xen-guest-image-minimal-raspberrypi4-64.ext3
>       > [23:40:15] <Guest9046> losetup: 
> xen-guest-image-minimal-raspberrypi4-64.ext3: No such file or directory
>       > [23:40:15] <Guest9046> root@raspberrypi4-64:~# losetup /dev/loop0 
> /home/root/xen-guest-image-minimal-raspberrypi4-64.ext3
>       > [23:40:15] <Guest9046> losetup: 
> /home/root/xen-guest-image-minimal-raspberrypi4-64.ext3: No such file or 
> directory
>       > [23:40:15] <Guest9046> root@raspberrypi4-64:~#
>       > [23:40:15] <Guest9046> root@raspberrypi4-64:~#
>       > [23:40:15] <Guest9046> root@raspberrypi4-64:~#
>       > [23:40:15] <Guest9046> root@raspberrypi4-64:~# losetup /dev/loop0 
> /home/root/xen-guest-image-minimal-raspberrypi4-64.ext3
>       > [23:40:15] <Guest9046> losetup: 
> /home/root/xen-guest-image-minimal-raspberrypi4-64.ext3: No such file or 
> directory

It looks like either
/home/root/xen-guest-image-minimal-raspberrypi4-64.ext3 doesn't exist or
/dev/loop0 doesn't exist

 
>       Why do you want to mount the file system ?
> 
>       Anyway this is not related to Xen, I guess you could start without xen 
> and still not manage to mount the file like that (linux
>       configuration issue ?)
> 
>       What is the content of you guest.cfg
>       How do you want to pass the guest root file system ?
> 
>       Yocto should actually generate an img file and you could use it by 
> having something like this in your guest.cfg:
>       disk=["file:/home/root/guest1.img,xvda,w”]
> 
>       Cheers
>       Bertrand
> 
>       >
>       > Any input on this issue will be really helpful, expecting your 
> response.
>       >
>       > Thanks & Regards,
>       > Vipul Kumar
> 
> 
>