Re: [Xen-devel] assembly-language mutex support

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Ah, I think this is related to difficulties supporting ‘negative segment accesses’. This means we have to rebuild glibc and we lose some NPTL functionality in doing that.

However, this problem is not present if you run a 64-bit hypervisor. You can run 64-bit or 32-bit (PAE) Linux guests on the 64-bit hypervisor with no limitations (even as domain 0) and the ‘negative segment access’ problem goes away.

You should try that out! The only tricky point may be if the distro you use has deliberately picked different glibc when running a 32-bit Xen version of Linux, despite the fact you are running on 64-bit hypervisor. In  that case you might have to tweak a ld.so config file to stop searching for nosegneg libraries.

But short answer is: use a 64-bit hypervisor and it should all work fine.

 -- Keir

On 4/4/08 22:30, "Bart Heinsius" <bheinsius@xxxxxxxxx> wrote:

I don't know what it means exactly, except that it hear it can cause problems for BDB.
I want to run a production Zimbra instance in a Xen vm and certain people at Zimbra advice me to not do that unless it has assembly-language mutex support, since BDB uses assembly level mutex locks by default.
I was pointed to:
https://bugzilla.redhat.com/show_bug.cgi?id=91933
http://www.openldap.org/lists/openldap-software/200603/msg00214.html

and
http://www.zimbra.com/forums/installation/14121-virtualization-zimbra.html

-- Bart

Keir Fraser wrote:

What does that even mean?

 -- Keir


On 4/4/08 21:45, "Bart Heinsius" <bheinsius@xxxxxxxxx> <mailto:bheinsius@xxxxxxxxx>  wrote:

  
 

Hi,

I read some time ago that Xen does not have assembly-language mutex support.
Is this still the case in Xen 3.2?

best regards,
Bart.


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