Supporting large dump files

Supporting large dump files

[Graham, Simon]

This may have come up before but I can't find it - with the default
build of Xen, libxc is built in a way that does not support large files
- this is a problem currently when attempting to dump domains larger
than 2GB - the dump eventually fails with:

[root@teller diag]# xm dump-core penn1
Dumping core of domain: penn1 ...
Error: Failed to dump core: (27, 'File too large')

My (admittedly limited) knowledge of this area leads me to the need to
define _FILE_OFFSET_BITS as 64; is there any issue with turning this on
for the tools/libxc build? Is there any other #define that should be
used instead of or in addition to this one?

Simon

RE: Supporting large dump files

[Ian Pratt]

> This may have come up before but I can't find it - with the 
> default build of Xen, libxc is built in a way that does not 
> support large files
> - this is a problem currently when attempting to dump domains 
> larger than 2GB - the dump eventually fails with:

PV save/restore seems to work fine for guests >4GB... 

Ian
 
> [root@teller diag]# xm dump-core penn1
> Dumping core of domain: penn1 ...
> Error: Failed to dump core: (27, 'File too large')
> 
> My (admittedly limited) knowledge of this area leads me to 
> the need to define _FILE_OFFSET_BITS as 64; is there any 
> issue with turning this on for the tools/libxc build? Is 
> there any other #define that should be used instead of or in 
> addition to this one?
> 
> Simon
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
> 

Re: Supporting large dump files

[Daniel P. Berrange]

On Wed, Feb 07, 2007 at 02:20:47PM -0500, Graham, Simon wrote:
> This may have come up before but I can't find it - with the default
> build of Xen, libxc is built in a way that does not support large files
> - this is a problem currently when attempting to dump domains larger
> than 2GB - the dump eventually fails with:
> 
> [root@teller diag]# xm dump-core penn1
> Dumping core of domain: penn1 ...
> Error: Failed to dump core: (27, 'File too large')
> 
> My (admittedly limited) knowledge of this area leads me to the need to
> define _FILE_OFFSET_BITS as 64; is there any issue with turning this on
> for the tools/libxc build? Is there any other #define that should be
> used instead of or in addition to this one?

What version of Xen are you using ? I submitted a patch to have this fixed
many months ago, and I'm pretty sure it was incorporated in Xen 3.0.4

Dan.
-- 
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RE: Supporting large dump files

[Graham, Simon]

> > My (admittedly limited) knowledge of this area leads me to the need
> to
> > define _FILE_OFFSET_BITS as 64; is there any issue with turning this
> on
> > for the tools/libxc build? Is there any other #define that should be
> > used instead of or in addition to this one?
> 
> What version of Xen are you using ? I submitted a patch to have this
> fixed
> many months ago, and I'm pretty sure it was incorporated in Xen 3.0.4
> 

Still on 3.0.3 at the moment - about to switch to 3.0.4 though. HOWEVER,
searching both the 3.0.4 and unstable sources, I don't see the specific
fix I am proposing in tools/libxc; can you tell me exactly what/where
your patch was?

Thanks,
Simon

PS: To answer Ian's point -- I agree that PV save/restore of guests >
2GB works; I have no idea at the moment why save/restore works and dump
does not but I can tell you that building with _FILE_OFFSET_BITS=64
makes the dump work... I'm just concerned that there might be some other
dependency that this breaks...

Re: Supporting large dump files

[Daniel P. Berrange]

On Wed, Feb 07, 2007 at 02:41:59PM -0500, Graham, Simon wrote:
> > > My (admittedly limited) knowledge of this area leads me to the need
> > to
> > > define _FILE_OFFSET_BITS as 64; is there any issue with turning this
> > on
> > > for the tools/libxc build? Is there any other #define that should be
> > > used instead of or in addition to this one?
> > 
> > What version of Xen are you using ? I submitted a patch to have this
> > fixed
> > many months ago, and I'm pretty sure it was incorporated in Xen 3.0.4
> > 
> 
> Still on 3.0.3 at the moment - about to switch to 3.0.4 though. HOWEVER,
> searching both the 3.0.4 and unstable sources, I don't see the specific
> fix I am proposing in tools/libxc; can you tell me exactly what/where
> your patch was?

changeset:   12476:729a6231de35
user:        kfraser@localhost.localdomain
date:        Fri Nov 17 09:54:48 2006 +0000
summary:     [TOOLS] Provide common LFS CFLAGS/LDFLAGS additions in Rules.mk.

Dan.
-- 
|=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
|=-           Perl modules: http://search.cpan.org/~danberr/              -=|
|=-               Projects: http://freshmeat.net/~danielpb/               -=|
|=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505  -=|