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Re: linux-image-*-dbg for squeeze?



Hi Lucas,

On Fri, Mar 05, 2010 at 09:07:50AM +0100, Lucas Nussbaum wrote:
> On 04/03/10 at 16:40 -0700, John Wright wrote:
> > Hi kernel team,
> > 
> > (Cc-ing -devel to get more eyes on the subject, since I'm soliciting
> > ideas here...  See [1] for some context.)
> > 
> > What would it take to get kernel debuginfo into squeeze?  As I
> > understand it, the main blockers were [2]:
> 
> Hi John,
> 
> I raised the same question a few weeks ago. See the thread starting at
> http://lists.debian.org/debian-devel/2010/02/msg00403.html

Agh, I totally missed that discussion.  Sorry to bring it back up in a
new thread...

> Summary:
> - Some buildds for slow arches are hosted on DSL lines, making it
>   unpractical to upload very large kernel images (my -dbg .deb takes
>   424 MB on amd64).
>   => Support could be limited to fast arches with well-connected
>   buildds: i386, amd64, powerpc, s390 and ia64
>   
> - Archive space problem
>   => Support could be limited to some flavours (like, only the standard
>   one, for a start)

I think we could live with those compromises. :)

> - Buildd disk space: not a problem on the fast arches
> 
> So, the major blockers seem to be network bandwidth (to upload the
> packages) and increased build time for the kernel maintainers. See
> http://lists.debian.org/debian-devel/2010/02/msg00472.html
> http://lists.debian.org/debian-devel/2010/02/msg00478.html
> 
> I wonder what we (as Debian) could do about it. Would it make sense to
> sponsor a very fast machine that the kernel team could use to build the
> kernels and upload from, replacing kernel-archive.buildserver.net ?

Makes sense to me, especially if it had good connectivity to ftp-master.
What would it take to make this happen?  And would it make building
debug info more palatable to the kernel team?

> > Another alternative would be to turn on the CONFIG_DEBUG_INFO and
> > CONFIG_KPROBES options, but strip the kernel and modules, but at least
> > provide some script a user could run to rebuild the kernel with the same
> > options and compiler to get the debug symbols.  Or maybe upload the
> > debuginfo packages to a separate archive?  There was some discussion
> > about a large data archive a few years ago, and Joerg mentioned in May
> > 2008 that such an archive setup was only a couple weeks out [3].  But I
> > haven't heard anything since then...
> 
> It isn't that complicated to build your own kernel image with debuginfo,
> and it takes 30 mins on a fast 8-cores system. My notes:
> apt-get install linux-image-2.6.32-3-amd64 linux-source-2.6.32 kernel-package
> tar xf /usr/src/linux-source-2.6.32.tar.bz2
> cd linux-source-2.6.32
> cp /boot/config-2.6.32-3-amd64 .config
> edit .config:
>  CONFIG_KPROBES=y
>  CONFIG_DEBUG_INFO=y
> make oldconfig
> export PATH="/usr/lib/ccache:$PATH"
> make-kpkg -j 16 --append-to-version +kprobes --revision=1 --initrd binary-arch

True, but it doesn't give you debug data you can use with the kernel
Debian actually ships (although it might if CONFIG_KPROBES=y and
CONFIG_DEBUG_INFO=y in the real kernel, but it were stripped...).  Part
of the appeal is being able to use systemtap and crash without also
basically having to be your own kernel maintainer.

-- 
John Wright <jsw@debian.org>


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