Re: a ton of kernel issues

[Konrad Rzeszutek Wilk <konrad@darnok.org>]

On Mon, Dec 12, 2011 at 10:44:08PM +0100, Tim Evers wrote:
> Hi folks,
> 
> please forgive me if I'm not 100% right on this list but I'm going mad
> about the current xen development as far as the pv_ops kernel are
> involved. I've been using Xen since 3.0 in various productive setups
> without any serious problems for years now.
> 
> And now, since the support for the "patched" distro-kernel like debian 5
> run out I'm trying to setup a working xen+pv_ops kernel with regard to
> cpu and ram hotplug and live migration. Nothing special I thought but
> hell I'm totally lost: After testing two month now dozens of
> combinations I was not able to find a single kernel / xen combination
> which supports the abovementioned features. Some crash after hotplug on

Did you try the latest and greatest? Meaning anything that is based on a
3.0 (or higher) kernel?

> a migrated domu, some crash right at the migration and some crash right
> at the start if vcpu_avail > vcpus.

Is this with more than 32 CPUs?

> 
> I've tested
> 
> xen-4.0
> xen-4.1
> 
> debian 6 32 and 64 bit (2.6.32-x kernel)
> ubuntu lucid 32 and 64 bit kernels including karmic, natty and even
> oneric backports

backports? Why not just .

Looking at your BUG, did you look in the .config to see if you
had MAXSMP or NR_CPUS defined? If you had MAXSMP, there was a bug
for that fixed in 2.6.39 time-frame (I think). And if you look
at the NR_CPUS, do you see the NR_CPUs > 0 virtual_cpus?


Otherwise, does the virgin kernel boot if you specify maxvcpus=vcpus
and then later on use xm to take CPUs away?


> 
> I've put some questions on the users mailinglist, wrote bug reports but
> today after two month work on this I'm as stuck as one can get.

Uh? Hm somehow we [kernel engineers] never got copied on it.
> 
> Is it possible that there is not a single working xen+pv_ops setup out
> there which matches my needs? I can't believe it.
> I appreciate _any_ hint!
> 
> Regards
> 
> Tim
> 
> http://lists.xen.org/archives/html/xen-users/2011-11/msg00553.html
> http://lists.xen.org/archives/html/xen-users/2011-11/msg00523.html
> http://lists.xen.org/archives/html/xen-users/2011-11/msg00295.html
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/893177

OK, so it says it brought 8 CPUs on .. and then it crashes afterwards.
So is that kernel compiled with CONFIG_NR_CPUS=8 or some higher value?

> 
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