Xen Paravirt

Xen Paravirt

[Chuck Short]

Hi,

So that Xen paravirt ops has made it upstream what is needed in order to use it?

Any pointers would be much appreciated.

Thanks
chuck

Re: Xen Paravirt

[Jeremy Fitzhardinge]

Chuck Short wrote:
> Hi,
>
> So that Xen paravirt ops has made it upstream what is needed in order
> to use it?
>
> Any pointers would be much appreciated.

Hm, I should prepare a documentation patch.

If you build the kernel with CONFIG_PARAVIRT=y, CONFIG_XEN=y and enable
the Xen console, block and net devices (they will default =y), then you
should be able to use the resulting kernel with an existing Xen
installation (it will also boot native).  Unfortunately you can't use
the same actual kernel image file in both cases, but you can use the
same modules.

To boot native: boot the bzImage file as usual.

To boot under Xen, use the vmlinux file as your kernel image (you can
strip and gzip it if you wish).

The console is hvc0, so you may need to pass console=hvc0 in your Xen
config.

Similarly, the blockfront device is /dev/xvd[abc...][123...]; you'll
probably need to pass the appropriate root= kernel command line option. 
It does not support stealing the hdX or sdX names, so that part of the
Xen config will be ignored.

Netfront appears as ethX as usual.

The kernel does not support balloon or suspend/migrate/resume yet, so
that won't work.  You should be able to cleanly shutdown/reboot the
domain via xm.

Tell me how it goes!

    J

Re: Xen Paravirt

[Nate Carlson]

On Wed, 18 Jul 2007, Jeremy Fitzhardinge wrote:
> If you build the kernel with CONFIG_PARAVIRT=y, CONFIG_XEN=y and enable 
> the Xen console, block and net devices (they will default =y), then you 
> should be able to use the resulting kernel with an existing Xen 
> installation (it will also boot native).  Unfortunately you can't use 
> the same actual kernel image file in both cases, but you can use the 
> same modules.

Just curious, will that change?  :)

------------------------------------------------------------------------
| nate carlson | natecars@natecarlson.com | http://www.natecarlson.com |
|       depriving some poor village of its idiot since 1981            |
------------------------------------------------------------------------

Re: Xen Paravirt

[Jeremy Fitzhardinge]

Nate Carlson wrote:
> On Wed, 18 Jul 2007, Jeremy Fitzhardinge wrote:
>> If you build the kernel with CONFIG_PARAVIRT=y, CONFIG_XEN=y and
>> enable the Xen console, block and net devices (they will default =y),
>> then you should be able to use the resulting kernel with an existing
>> Xen installation (it will also boot native).  Unfortunately you can't
>> use the same actual kernel image file in both cases, but you can use
>> the same modules.
>
> Just curious, will that change?  :)

Yeah, it's a work in progress.  I have some test patches to extend the
bzImage format to contain ELF notes, and a corresponding Xen patch to
add a new file format for the domain builder. But its a bit
up-in-the-air because nobody has agreed to the bzImage format changes,
and its all a bit subtle to make sure it keeps working with a wide range
of fairly poorly implemented bootloaders.

    J

Re: Xen Paravirt

[Ian Campbell]

On Wed, 2007-07-18 at 18:45 -0400, Chuck Short wrote:
> So that Xen paravirt ops has made it upstream what is needed in order to use it?

I haven't been able to test yet but hopefully the xen-unstable build
system should already be prepared for this.

For now you can use:
	make linux-2.6-tip-build LINUX_VER=2.6-git

Once the next -rc comes out you can use:
	make linux-2.6-rc-build (/-dist/-install/-prep/-etc)

Once a real release is available the linux-2.6-tip-FOO without the
LINUX_VER should work.

All the above should work using
	make KERNELS="linux-2.6-xen linux-2.6-tip" dist
and friends as well. You need the -xen still for domain 0.

Finally, you need XEN_TARGET_ARCH=x86_32 since only 32 bit is currently
supported.

Ian.