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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:
> 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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