Where are debug symbols for backported packages?

Question

Where can I download Linux kernel 2.6.35-25 debug symbols for kernel that comes from lucid-backports repository (I have enabled lucid-backports repository on Ubuntu 10.04 in /etc/apt/sources.list)?

The problem with debug symbols located here is that debug symbols for 2.6.35-25 linux kernel server image does not match with the binary I get from lucid back-ports repository:

ii linux-image-2.6.35-25-server
2.6.35-25.44~lucid1 Linux kernel image for version 2.6.35 on x86 ii linux-image-2.6.35-25-server-dbgsym
2.6.35-25.44 Linux kernel debug image for version 2.6.35

And hence the system-tap (stap) fails:

root@www:~/stap# stap para-callgraph-verbose.stp 'kernel.function("@fs/proc.c")' 'kernel.function("vfs_read")' -c "cat /proc/sys/vm/*"

ERROR: Build-id mismatch: "kernel" vs. "vmlinux-2.6.35-25-server"

There are also some reasons why I would prefer not to build linux kernel myself just to get stap working.

Answer 1

You should post your repository list so we can see how you've added it. I would firstly report the problem to the kernel backports people, they're the only people who can sort the issue out permanently or explain why they won't.

See: https://help.ubuntu.com/community/ReportingBugs

Secondly, you could do an easier compile of the kernel by using the source package to generate a deb with symbols:

apt-get source linux-kernel
etc

Answer 2

The page on ddebs.ubuntu.com that you linked to only contains the ddebs for packages built from the linux source package. However, the backported kernels are not built from that source package; they instead come from the linux-lts-backport-maverick source package:

(lucid-amd64)evan@caron:~$ apt-cache show linux-image-2.6.35-25-server | grep '^Source'
Source: linux-lts-backport-maverick

By contrast, here is the same query on the kernel released with Ubuntu 10.04 (which was 2.6.32):

(lucid-amd64)evan@caron:~$ apt-cache show linux-image-2.6.32-21-server | grep '^Source'
Source: linux

If you instead look at the ddebs page for the linux-lts-backport-maverick source package, you'll find ddebs for the kernel you're using.

As a side note, in spite of their name, the LTS backport kernels are released to the Updates pocket (e.g. lucid-updates), not to the Backports pocket (lucid-backports), as they are not backported through the Ubuntu Backports project. Due to their limited level of support, packages which are backported as true backports do not have debug symbols available on ddebs.ubuntu.com in order to save space.