[9fans] xen3 and pae problems

[9fans] xen3 and pae problems

[John Osborne]

Hi,
I've been working on getting a plan9 guest running under xen3, with
debian 4.0 as the host os/Dom0.  I've been running into a problem of
xen not wanting anything to do with the plan9 kernels - from what I've
been able to find from the logs, is that the xen hypervisor is set up
for PAE. Turns out PAE is setup by default with the linux-xen kernels
in debian.  There is a non-PAE hypervisor, but that would require me
to build a new kernel. Joy.
 Are there any plans to have a set of install/cpu kernels available
with that type of support, or should I start recompiling my linux
kernel to remove PAE?

Thanks in advance.
-- 
John Osborne
osborne6@ieee.org/osborne6@gmail.com/jro@freeshell.org

Re: [9fans] xen3 and pae problems

[Richard Miller]

> Turns out PAE is setup by default with the linux-xen kernels
> in debian.  There is a non-PAE hypervisor, but that would require me
> to build a new kernel.

It appears there are separate packages 'xen3' and 'xen3-pae' for
debian.  So you shouldn't need to build a kernel - just use the
appropriate package.

Re: [9fans] xen3 and pae problems

[John Osborne]

I've tried using the non-pae package and setting grub to load the
non-pae hypervisor.  The hypervisor then complains that the Dom0 linux
kernel has pae enabled.

>From what I've googled, PAE was enabled by default in the linux kernel
in Debian Etch back in February or so, breaking alot of stuff in what
was testing.  I've found a few similar messages on other lists
relating to Fedora, RHEL5, and CentOS as having PAE enabled in the
kernel, as well as instructions/notes on how to build a non-PAE linux
kernel, so one can run the non-PAE xen hypervisor, thus being able to
run non-PAE enabled/capable/etc guest Doms under xen.

I've been considering just installing NetBSD to work around this :P

I probably should search a little bit more...

On 4/17/07, Richard Miller <9fans@hamnavoe.com> wrote:
> > Turns out PAE is setup by default with the linux-xen kernels
> > in debian.  There is a non-PAE hypervisor, but that would require me
> > to build a new kernel.
>
> It appears there are separate packages 'xen3' and 'xen3-pae' for
> debian.  So you shouldn't need to build a kernel - just use the
> appropriate package.
>
>


-- 
John Osborne
osborne6@ieee.org/osborne6@gmail.com/jro@freeshell.org

Re: [9fans] xen3 and pae problems

[Richard Miller]

> I've tried using the non-pae package and setting grub to load the
> non-pae hypervisor.  The hypervisor then complains that the Dom0 linux
> kernel has pae enabled.

Doesn't the non-pae xen package include a dom0 kernel?  If not, it
looks like you will indeed have to build one.

Re: [9fans] xen3 and pae problems

[John Osborne]

the xen packages only include the hypervisor 'kernel', not the
associated linux kernel that xen ends up starting for Dom0...

Out of curiosity, has anyone started work on PAE support for plan9?

On 4/17/07, Richard Miller <9fans@hamnavoe.com> wrote:
> > I've tried using the non-pae package and setting grub to load the
> > non-pae hypervisor.  The hypervisor then complains that the Dom0 linux
> > kernel has pae enabled.
>
> Doesn't the non-pae xen package include a dom0 kernel?  If not, it
> looks like you will indeed have to build one.
>
>


-- 
John Osborne
osborne6@ieee.org/osborne6@gmail.com/jro@freeshell.org

Re: [9fans] xen3 and pae problems

[erik quanstrom]

i've looked at it.

what do you mean by PAE support?  what would plan 9 need to
do to play nicely with xen3?

pae is already recognized by plan 9, but the default memory types are not
fiddled and you can't map a region with a specific pae type.

these changes are not too hard, but i haven't gotten to a place yet
where i need to implement anything but it may be that setting up
wc pci space will be necessiary for good performance with some 
pcie drivers. 

- erik

On Tue Apr 17 09:54:10 EDT 2007, osborne6@gmail.com wrote:
> the xen packages only include the hypervisor 'kernel', not the
> associated linux kernel that xen ends up starting for Dom0...
> 
> Out of curiosity, has anyone started work on PAE support for plan9?
> 
> On 4/17/07, Richard Miller <9fans@hamnavoe.com> wrote:
> > > I've tried using the non-pae package and setting grub to load the
> > > non-pae hypervisor.  The hypervisor then complains that the Dom0 linux
> > > kernel has pae enabled.
> >
> > Doesn't the non-pae xen package include a dom0 kernel?  If not, it
> > looks like you will indeed have to build one.

Re: [9fans] xen3 and pae problems

[ron minnich]

your best bet with xen has always been to build a hypervisor and
kernel from scratch. The packages, in my experience, are only useful
for linux users.

THX on 9grid.net has a hypervisor and kernel that will boot plan 9...

ron

Re: [9fans] xen3 and pae problems

[John Osborne]

I'll take a look at that.  Personally, I'd rather stick with the
packages - slightly newer kernel with etch (the patched stuff from xen
looks like it's still 2.6.16 or something? isn't 9p borked in that
kernel release?).

If all else fails, I've got a spare 15Gb partition to run plan9
natively or set up NetBSD for Dom0.

Thanks again guys!

On 4/17/07, ron minnich <rminnich@gmail.com> wrote:
> your best bet with xen has always been to build a hypervisor and
> kernel from scratch. The packages, in my experience, are only useful
> for linux users.
>
> THX on 9grid.net has a hypervisor and kernel that will boot plan 9...
>
> ron
>


-- 
John Osborne
osborne6@ieee.org/osborne6@gmail.com/jro@freeshell.org