Xen users - Jul 2006 - Using Linux 2.4 custom domu on x86_64 2.6 Xen dom0

Hi group,

I have searched the archives and found some clues to making this work, but all
is not clear yet.

Here''s what I need to do:
Run 10 domu''s using custom Linux 2.4.27 kernel with a number of patches
on a Xen dom0. Each server in our current non-Xen environment requires 1GB ram,
and I am assuming about the same usage in a Xen environment plus a bit of
overhead.


Here''s the hardware/base system I''m using:
Dell 1855 blade servers Dual 3.0ghz 12GB ram. These can run either x86 32-bit,
or x86_64. The base system is CentOS 4.3.


Where I''m at:
1) I figure 10 domu''s should run on each blade depending on the final
overhead of the Xen system.
2) I believe Xen 3.x is not an option as there is no current port of a Linux 2.4
domu Kernel. Am I right that only Linux 2.6 is ported to Xen 3.x for domu?
3) To use more than 4GB ram, it looks like I have to use either
xen-unstable-install-x86_32p.tgz (PAE >4GB support), or
xen-unstable-install-x86_64.tgz (since Xen 3.x is probably not an option),
depending on the base system I run (eg. Cenos4.3 x86 or x86_64).

Big question:
How do I make 2.4.27 kernel with my patches Xenified for domu use in
xen-unstable-install-x86_x?

In the xen-2.0.7-src.tgz file, I see there is a linux-2.4.30-xen-sparse
directory. Do I have to add my patches to a vanilla 2.4.30 kernel, then compile
it somehow under the Xen source tree? Can I drop my current 2.4.27 sources into
the Xen tree, then compile and smile?


Any help at all would be appreciated.

Brian




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Hello Mr. Zammit,

On Mon, 2006-24-07 at 10:49 -0700, Brian wrote:
> Big question:
> How do I make 2.4.27 kernel with my patches Xenified for domu use in
> xen-unstable-install-x86_x? 
No idea: that is, I don''t know the specifics.  Stuff here and at
clients'' is all running RHEL 4/CentOS 4, so I haven''t had to
deal with
2.4 kernels.
> In the xen-2.0.7-src.tgz file, I see there is a
> linux-2.4.30-xen-sparse directory. Do I have to add my patches to a
> vanilla 2.4.30 kernel, then compile it somehow under the Xen source
> tree? Can I drop my current 2.4.27 sources into the Xen tree, then
> compile and smile?
The xen patches "xenify" the vanilla Linux kernel.  Taking the xen
patches and applying them to a non-vanilla kernel _may_ work, but I
suspect it will depend on how heavily customized your kernel is.
Judging from your post, I''m assuming there''s a lot of patching
in your
customized kernel.  I foresee breakage.

Your best bet is to forgo trying to patch your kernel and move to full
virtualization under xen.  Besides, sticking with xen 2.0.blah is asking
for trouble - too much good stuff in the 3.0 release.

Good luck,

Ranbir

-- 
Kanwar Ranbir Sandhu
Linux 2.6.17-1.2141_FC4 i686 GNU/Linux 
23:21:21 up 1 day, 35 min, 2 users, load average: 0.75, 0.50, 0.40 



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> -----Original Message-----
> From: xen-users-bounces@lists.xensource.com 
> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Brian
> Sent: 24 July 2006 18:50
> To: xen-users@lists.xensource.com
> Subject: [Xen-users] Using Linux 2.4 custom domu on x86_64 
> 2.6 Xen dom0
> 
> Hi group,
> 
> I have searched the archives and found some clues to making 
> this work, but all is not clear yet. 
> 
> Here''s what I need to do:
> Run 10 domu''s using custom Linux 2.4.27 kernel with a number 
> of patches on a Xen dom0. Each server in our current non-Xen 
> environment requires 1GB ram, and I am assuming about the 
> same usage in a Xen environment plus a bit of overhead.
The math here is fine. 
> 
> 
> Here''s the hardware/base system I''m using:
> Dell 1855 blade servers Dual 3.0ghz 12GB ram. These can run 
> either x86 32-bit, or x86_64. The base system is CentOS 4.3.
> 
> 
> Where I''m at:
> 1) I figure 10 domu''s should run on each blade depending on 
> the final overhead of the Xen system. 
> 2) I believe Xen 3.x is not an option as there is no current 
> port of a Linux 2.4 domu Kernel. Am I right that only Linux 
> 2.6 is ported to Xen 3.x for domu?
> 3) To use more than 4GB ram, it looks like I have to use 
> either xen-unstable-install-x86_32p.tgz (PAE >4GB support), 
> or xen-unstable-install-x86_64.tgz (since Xen 3.x is probably 
> not an option), depending on the base system I run (eg. 
> Cenos4.3 x86 or x86_64).
> 
> Big question:
> How do I make 2.4.27 kernel with my patches Xenified for domu 
> use in xen-unstable-install-x86_x? 
> 
> In the xen-2.0.7-src.tgz file, I see there is a 
> linux-2.4.30-xen-sparse directory. Do I have to add my 
> patches to a vanilla 2.4.30 kernel, then compile it somehow 
> under the Xen source tree? Can I drop my current 2.4.27 
> sources into the Xen tree, then compile and smile?
Theoretically this will work. However, the Xen 2.x and Xen 3.x are
different API''s, and thus you will not be able to run your 2.x kernel
on
3.x. Not even the slightest chance - it''s blocked. And even if it
wasn''t
blocked, it''s not compatible enough to even have a chance of working...

Since you want to run more than 4 1GB DomU on one guest (presumably to
save hardware cost), I can''t really see any way to solve this, as Xen
2.x doesn''t support PAE or x86_64. 

The only viable solutions are:
1. Upgrade your kernel to 2.6.16 or so, and apply the relevant patches
here. 
2. Run fully virtualized (VT/SVM technology) on x86_64 or 32-bit PAE. 
3. Run fewer guest per blade (possibly on a less expensive blade-model
with fewer cores/CPU''s and less memory slots).

--
Mats
> 
> 
> Any help at all would be appreciated.
> 
> Brian
> 
> 
> 
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
> 
> 
> 


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Hello Mr. Sandhu,

It has been a while since we chatted.

>On Mon, 2006-24-07 at 10:49 -0700, Brian wrote:
>> Big question:
>> How do I make 2.4.27 kernel with my patches Xenified for domu use in
>> xen-unstable-install-x86_x? 
>No idea: that is, I don''t know the specifics.  Stuff here and at
>clients'' is all running RHEL 4/CentOS 4, so I haven''t had
to deal with
>2.4 kernels.
I''d like to say the same about our use of kernel versions, but we are
still weeding out the hardened, customized, 2.4 kernels used here.

>> tree? Can I drop my current 2.4.27 sources into the Xen tree, then
>> compile and smile?
>Judging from your post, I''m assuming there''s a lot of
patching in your
>customized kernel.  I foresee breakage.
Yes, its heavily customized and I''m trying to get it
standardized/simplified/upgraded. A lot of the patching was done to overcome
missing features in 2.4, but 2.6 has (almost) everything needed for our
application now.
>Your best bet is to forgo trying to patch your kernel and move to full
>virtualization under xen.  Besides, sticking with xen 2.0.blah is asking
>for trouble - too much good stuff in the 3.0 release.
Yes, it looks like Xen 3.0 and the 2.6 kernel update are the next stop.
We''ve been planning an update to 2.6 anyways, but this will force the
work to the forefront. As in today.
>Good luck,
Thanks. It''s going to be a long day (there''s still 25 hours in
a day, right?)


Brian





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>Since you want to run more than 4 1GB DomU on one guest (presumably to
>save hardware cost), I can''t really see any way to solve this, as
Xen
>2.x doesn''t support PAE or x86_64. 
I looked at the source files again, and realized the unstable tarball is
actually 3.x, not 2.x made to work with pae or x86_64 as I had first thought. So
right you are: 3.x is the only possible choice in my case.
>The only viable solutions are:
>1. Upgrade your kernel to 2.6.16 or so, and apply the relevant patches
>here. 
That''s my next stop. I hoped to delay the recompile of our application
servers to use 2.6 until a later time, but that delay doesn''t seem
possible. Time to transfer my stumblings into the devel list.
>2. Run fully virtualized (VT/SVM technology) on x86_64 or 32-bit PAE. 
The blades we''re using don''t have the VT processors in them.
Maybe the next round will, though from what I have seen on current performance
comparisons I might want to run paravirtualized anyways.
>3. Run fewer guest per blade (possibly on a less expensive blade-model
>with fewer cores/CPU''s and less memory slots).
It''s a server per U of rack space issue. Getting 4 virtual servers out
of each blade instead of 10 will not fly.

Thanks for the clarifications. Onward to upgrading.

Brian





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Dear all,

Where can I download the source (.tar.gz or .bz2, not RPMs!!!!)
of Xen-3.0 for RHEL?

Thank you in advance,
Arsen.

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On 7/25/06, Arsen Hayrapetyan <ahairape@mail.cern.ch>
wrote:
> Dear all,
>
> Where can I download the source (.tar.gz or .bz2, not RPMs!!!!)
> of Xen-3.0 for RHEL?
1) sources aren''t for any specific distribution...

2) Where did you look for sources? It''s a bit hidden on the download
page - you have to follow the link in the "tarballs - Pre-built
installations of Xen 3.0 for 32 bit, PAE and 64 bit." section.


Maybe someone from xensource, who eventually reads that this question
comes up again and again, may find the time to add a hint that sources
can also be found behind the tarbvalls link" Actually the word
"sources" doesn''t appear at all on the download page - that
isn''t
exactly what can be said as good web usability...

Henning

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