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Re: [Xen-users] xen on amd64 or intel

Hello Nicholas,

I used xen 3.0.1 with 64-bit debian sarge for dom0, and several 64-
and 32-bit sarge domU's. The domU kernel was 64-bit even for the
32-bit linux'es. Hardware is amd64 (venice) with 4GB memory.

This worked quite good for several applications that require 32-bit
linux. However I had no chance to get DB2(*) running in such a 32-bit
domU. The problem was that DB2 did not find any shared memory at all,
a "ipcs -l" did not show any shared memory limits in such a 32-bit
domU, but only something as:

        ------ Shared Memory Limits --------
        ------ Semaphore Limits --------
        max number of arrays = 1024
        max semaphores per array = 250
        max semaphores system wide = 32000
        max ops per semop call = 32
        semaphore max value = 32767
        ------ Messages: Limits --------
        max queues system wide = 1024
        max size of message (bytes) = 8192
        default max size of queue (bytes) = 16384

Shutting down such a 32-bit domU also most time resulted in a zombie.
I finally moved everything back to plain 32-bit (with PAE to make use
of all 4 GB memory).

I don't know if this was fixed yet, or I maybe should have tried to
use a 32-bit kernel for the domU's. I might give it another try as
soon as etch is stable.

(*) DB2 is also available as 64-bit, however it will not work on
    debian amd64 because it is not plain 64-bit but a mixture of 64-
    and 32-bit programs. Same for Oracle btw.

You wrote at Freitag, 21. April 2006 01:36:

NL> On 4/12/06, Heiko Wundram <me+xen-users@xxxxxxxxxxxxx> wrote:
>> Something similar here: AMD64 with 4GB RAM running a 64-bit Gentoo Dom0,
>> running 30 DomUs, which are mixed 32-bit Debian/SuSE/FC4/CentOS and 64-bit
>> Gentoo, but all with a 64-bit kernel for the DomU. If you don't choose
>> stupid
>> compiler-settings (beware of -Os, it creates broken code), it's running
>> very,
>> very smoothly.

NL> One question I've been meaning to ask, and I haven't had the time to check
NL> myself is if there are problems when using a  64bit domU kernel with modules
NL> and 32bit userland modutils in Debian or other distributions.

NL> Does a 32bit userland imply the need for static non-module kernels?

NL> --
NL> Nicholas Lee
NL> http://stateless.geek.nz
NL> gpg 8072 4F86 EDCD 4FC1 18EF  5BDD 07B0 9597 6D58 D70C

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