Re: [Xen-users] Xen 4.0 Custom kernels

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Fri, May 14, 2010 at 07:47:33AM -0300, Net Warrior wrote:
>    Hi There.
>    The hardware is the same, so I asume that the initramfs used for Dom0
>    could be used for DomU as well
>

No, the hardware is not the same!

domU only has "virtual" hardware provided by Xen, which is totally different 
from the physical hardware dom0 has access to!


, and yes I specified the root partition in
>    the DomU config file as well something like root /dev/sda1 ro , should I
>    use xdev as well in there?
>    Thanks for your time and support.
>

Please paste your /etc/xen/<guest> cfgfile.

-- Pasi

>    Best Regards
>    2010/5/14 Pasi Kärkkäinen <[1]pasik@xxxxxx>
> 
>      On Thu, May 13, 2010 at 07:40:51PM -0300, Net Warrior wrote:
>      > Hi there guys
>      >
>      > As a test, I started using the same kernel and initramfs like in Dom0
>      > which i know it works, but when starting up DomU I've get.
>      >
>      > switchroot: mount failed: No such file or directory
>      > Kernel panic - not syncing: Attempted to kill init!
>      > Pid: 1, comm: init Not tainted 2.6.31.13 #14
>      >
> 
>      So the dom0 initrd image is not suitable for domU, ie. it doesn't load
>      xen block frontend driver.. most probably. So the domU kernel is
>      not able to access the virtual disks provided to it.
>      > I've got the same error while setting up Dom0 and was a problem with
>      > the scsi modules which I included in the kernel and not in the
>      > initramfs, my bad !!
>      >
>      > My config file looks this.
>      >
>      
> #----------------------------------------------------------------------------
>      > # Kernel image file.
>      > kernel = "/boot/vmlinuz-2.6.31.13"
>      >
>      > # Optional ramdisk.
>      > ramdisk = "/boot/initrd-2.6.31.13.img"
>      >
>      > disk = [ 'phy:VG-NW/root,sda1,w','phy:VG-NW/swap,sda2,w' ]
>      >
> 
>      You should use xvda1 and xvda2 here, not sda1 and sda2.
>      the sd* naming is deprecated for xen PV guests.
>      > Also copied the /lib/modules/kernel_version to the *guest* partition.
>      >
>      > What am I missing?
>      >
> 
>      You need to create an initrd image that is suitable for the domU.
> 
>      Also did you specify root= parameter for the domU kernel?
>      -- Pasi
> 
>      > Thanks for your time and support
>      > Regards
>      >
>      >
>      >
>      >
>      >
>      >
>      >
>      >
>      > 2010/5/13, Pasi Kärkkäinen <[2]pasik@xxxxxx>:
>      > > On Thu, May 13, 2010 at 02:38:40PM -0300, Net Warrior wrote:
>      > >> Hi Pasi.
>      > >>
>      > >> Did not know I could use the Vanila Kernel for DomU usage, I
>      thought
>      > >> it has to be patched somehow as well.. so good news, I'll try to
>      > >> compile a custom one using the latest stable from [3]kernel.org and
>      leave
>      > >> the Dom0 which is working as it is.
>      > >>
>      > >
>      > > I recommend using the latest stable 2.6.32.x kernel for the domU.
>      > >
>      > > If you're building a 32bit domU kernel remember it needs to be PAE
>      (64G mem
>      > > support),
>      > > otherwise you won't see the pvops Xen domU options at all in the
>      kernel
>      > > configuration.
>      > >
>      > > There are no special requirements for 64bit domU kernel.
>      > >
>      > > -- Pasi
>      > >
>      > >> Thanks for your time and support
>      > >> Regards
>      > >>
>      > >>
>      > >>
>      > >>
>      > >>
>      > >> 2010/5/13, Pasi Kärkkäinen <[4]pasik@xxxxxx>:
>      > >> > On Thu, May 13, 2010 at 12:38:00PM -0300, Net Warrior wrote:
>      > >> >>    Hi there guys.
>      > >> >>
>      > >> >>    I'm using CentOS 5.4, I was able to compile my custom Dom0
>      kernel
>      > >> >> and
>      > >> >> boot
>      > >> >>    it, now I've got some doubts.
>      > >> >>
>      > >> >>    I'd like to compile a custom DomU image, the problem is that
>      when I
>      > >> >> do,
>      > >> >>    make kernels KERNELS="linux-2.6-xen0 linux-2.6-xenU" it tries
>      to
>      > >> >> download
>      > >> >>    the kernel
>      > >> >>    from the HG repository which seems to have old 2.6.18
>      kernels, I
>      > >> >> want
>      > >> >> to
>      > >> >>    use the GIT repository which is alrealdy downloaded and is
>      the
>      > >> >> source I
>      > >> >>    used to complile Dom0 using
>      > >> >>    kernel 2.6.33.13.
>      > >> >>
>      > >> >
>      > >> > specifying KERNELS="linux-2.6-xen0 linux-2.6-xenU" will compile
>      > >> > linux-2.6.18-xen,
>      > >> > that's how it should be.
>      > >> >
>      > >> > If you don't specify KERNELS= at all, then it'll build
>      linux-2.6.31.x
>      > >> > kernel.
>      > >> > Or alternatively you can specify KERNELS="linux-2.6-pvops" to get
>      the
>      > >> > same
>      > >> > result.
>      > >> >
>      > >> >>    Question:
>      > >> >>    Which files do I have to modify or how do I have to proceed
>      to
>      > >> >> achieve
>      > >> >>    what I want?
>      > >> >>
>      > >> >
>      > >> > Did you know you can use the *default* (vanilla) [5]kernel.org
>      Linux
>      > >> > kernels as
>      > >> > Xen PV domU?
>      > >> > No patches needed for that, the upstream kernels will work for
>      domU.
>      > >> >
>      > >> >>    Under /usr/src/xen-4.0.0/buildconfigs I can see some files
>      which
>      > >> >> define
>      > >> >>    some stuff depending on what I chose but not sure if it's
>      safe to
>      > >> >> mees
>      > >> >>    with this.
>      > >> >>
>      > >> >>    Thanks for your time and support.
>      > >> >
>      > >> > Hopefully that helps.
>      > >> >
>      > >> > -- Pasi
>      > >> >
>      > >> >
>      > >
> 
> References
> 
>    Visible links
>    1. mailto:pasik@xxxxxx
>    2. mailto:pasik@xxxxxx
>    3. http://kernel.org/
>    4. mailto:pasik@xxxxxx
>    5. http://kernel.org/

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