Xen users - Aug 2010 - Need help in compiling and installing Xen-3.4.1 on Lucid

Hi,

I am a Xen newbie and have been trying to get Xen-3.4.1 working on my Ubuntu
Lucid (kernel version 2.6.32-21) system, using kernel 2.6.18.8 as dom0. In
attempting this, I ran into the following issue. On booting into Xen, I get
these errors:

Mounting none on /dev failed. No such device.
...
Gave up waiting for root device.
...
Alert! Could not mount /dev/sda1 as root device. Dropping to a shell.

After this I get a (initramfs) shell. I figured out that this is due to the
fact that a 2.6.18 kernel doesn''t support devtmpfs, which is the /dev
filesystem Lucid uses. Now I would like to compile a newer kernel and use it
as dom0. However, I could not find Xen-patched kernels that might have
devtmpfs support (version >= 2.6.32). What are the steps I should take to
get, patch and install such a kernel as dom0 (rather than falling back to
the default kernel that Xen make scripts download from Mercurial repos)?

[Please point me to any documentation that I might have missed regarding
this.]

Regards,
D.


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On Wed, Aug 25, 2010 at 3:09 PM, Daniel Mathew <danieljmathew@gmail.com>
wrote:
> Hi,
>
> I am a Xen newbie and have been trying to get Xen-3.4.1 working on my
Ubuntu
> [Please point me to any documentation that I might have missed regarding
> this.]
For Xen 4, there''s http://wiki.xensource.com/xenwiki/Xen4.0, look at
"tutorials" section.

Note that latest pv_ops kernel used on that tutorial might not work
for earlier versions of Xen, so if you simply want to find newer
kernel that works with Xen 3.4.1, you might want to try kernel 2.6.34
+ patch on http://code.google.com/p/gentoo-xen-kernel/downloads/list

-- 
Fajar

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Thank you for the reply, Fajar.

I was looking for a patched version of the vanilla kernel (or even
Ubuntu/Debian/Fedora). It would be great if I could even generate a patch
myself somehow - is this possible using the Xen-3.4.1 source and makefiles?

D.

On Fri, Aug 27, 2010 at 7:34 AM, Fajar A. Nugraha <fajar@fajar.net> wrote:
> On Wed, Aug 25, 2010 at 3:09 PM, Daniel Mathew
<danieljmathew@gmail.com>
> wrote:
> > Hi,
> >
> > I am a Xen newbie and have been trying to get Xen-3.4.1 working on my
> Ubuntu Lucid (kernel version 2.6.32-21) system, using kernel 2.6.18.8 as
> dom0. In attempting this, I ran into the following issue. On booting into
> Xen, I get these errors:
>
> Mounting none on /dev failed. No such device.
> ...
> Gave up waiting for root device.
> ...
> Alert! Could not mount /dev/sda1 as root device. Dropping to a shell.
>
> After this I get a (initramfs) shell. I figured out that this is due to the
> fact that a 2.6.18 kernel doesn''t support devtmpfs, which is the
/dev
> filesystem Lucid uses. Now I would like to compile a newer kernel and use
it
> as dom0. However, I could not find Xen-patched kernels that might have
> devtmpfs support (version >= 2.6.32). What are the steps I should take
to
> get, patch and install such a kernel as dom0 (rather than falling back to
> the default kernel that Xen make scripts download from Mercurial repos)?
>
> > [Please point me to any documentation that I might have missed
regarding
> > this.]
>
> For Xen 4, there''s http://wiki.xensource.com/xenwiki/Xen4.0, look
at
> "tutorials" section.
>
> Note that latest pv_ops kernel used on that tutorial might not work
> for earlier versions of Xen, so if you simply want to find newer
> kernel that works with Xen 3.4.1, you might want to try kernel 2.6.34
> + patch on http://code.google.com/p/gentoo-xen-kernel/downloads/list
>
> --
> Fajar
>

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On Fri, Aug 27, 2010 at 12:27 PM, Daniel Mathew <danieljmathew@gmail.com>
wrote:
> Thank you for the reply, Fajar.
>
> I was looking for a patched version of the vanilla kernel
That''s the link I gave you. Patches for vanilla kernel. Have you looked
at it?
http://code.google.com/p/gentoo-xen-kernel/downloads/list contains
patches for corresponding version of vanilla kernel to have old
xenlinux-style kernel that should work with Xen 3.4. Personally I use
2.6.34 as dom0 with Xen 4.0.0, and as domU with Xen 3.3.1.

The kernel can be build separately from xen (i.e. you don''t need Xen
source or Makefile to build the kernel). You just need to select the
appropriate kernel options (during "make menuconfig" or whatever) to
enable Xen support (which BTW is different options compared to pv_ops
kernel). See
http://lists.xensource.com/archives/html/xen-users/2010-07/msg00452.html
> (or even Ubuntu/Debian/Fedora).
> It would be great if I could even generate a patch
> myself somehow - is this possible using the Xen-3.4.1 source and makefiles?
xen versions can generally be uncoupled from kernel version in Linux
dom0, so usually you don''t need to have one-to-one mapping between
kernel version 2.6.x and xen version y. However, newest version of
pv_ops kernel requires some features only present in Xen 4.0.1 (or
some hg revisions after xen 4.0.0), so it might not work for
Xen-3.4.1. AFAIK the kernel source by itself has not been distributed
inside the Xen-3.4.1 source tarball, and only downloaded during xen
build process.

-- 
Fajar

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Thanks for the reply, Fajar. My apologies for the late reply. I hadn''t
looked inside the files; instead I assumed that they''re
Gentoo-specific,
from the URL.

Daniel.

On Fri, Aug 27, 2010 at 11:25 AM, Fajar A. Nugraha <fajar@fajar.net>
wrote:
> On Fri, Aug 27, 2010 at 12:27 PM, Daniel Mathew
<danieljmathew@gmail.com>
> wrote:
> > Thank you for the reply, Fajar.
> >
> > I was looking for a patched version of the vanilla kernel
>
> That''s the link I gave you. Patches for vanilla kernel. Have you
looked at
> it?
> http://code.google.com/p/gentoo-xen-kernel/downloads/list contains
> patches for corresponding version of vanilla kernel to have old
> xenlinux-style kernel that should work with Xen 3.4. Personally I use
> 2.6.34 as dom0 with Xen 4.0.0, and as domU with Xen 3.3.1.
>
> The kernel can be build separately from xen (i.e. you don''t need
Xen
> source or Makefile to build the kernel). You just need to select the
> appropriate kernel options (during "make menuconfig" or whatever)
to
> enable Xen support (which BTW is different options compared to pv_ops
> kernel). See
> http://lists.xensource.com/archives/html/xen-users/2010-07/msg00452.html
>
> > (or even Ubuntu/Debian/Fedora).
> > It would be great if I could even generate a patch
> > myself somehow - is this possible using the Xen-3.4.1 source and
> makefiles?
>
> xen versions can generally be uncoupled from kernel version in Linux
> dom0, so usually you don''t need to have one-to-one mapping between
> kernel version 2.6.x and xen version y. However, newest version of
> pv_ops kernel requires some features only present in Xen 4.0.1 (or
> some hg revisions after xen 4.0.0), so it might not work for
> Xen-3.4.1. AFAIK the kernel source by itself has not been distributed
> inside the Xen-3.4.1 source tarball, and only downloaded during xen
> build process.
>
> --
> Fajar
>

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