What is going on with /sys/kernel/notes ?

mvirts@lemmy.world to Linux@lemmy.ml – 21 points –

Any thoughts on why cat /sys/kernel/notes gives me:

LinuxLinuXen@ XenlinuxXen2.Xenxen-3.Xen����XenXen��&����� XenXeXeXen������XeXengenericXen Xenyes

I'm beginning to look into another issue I posted about, but this struck me as odd

3

It was added in a patch to 2.6.23

Notes from the coder:

The bonus feature in my patch series adds the magic file /sys/kernel/notes. Reading this gives you the binary contents of the ELF notes section built into the kernel. Here you can find the build ID of the running kernel. This gives a solution to a problem that has arisen for systemtap users, where nothing prevents them from using the kernel-debuginfo.i586 data to drive Systemtap's probe details, but are actually running the kernel from the kernel.i686 rpm. This is a failure on many levels, but some simple sanity-checking at the bottom always helps. Now it is easy to verify you have the right debuginfo file for the kernel you are running.

This is incorporated upstream now.

Yep, from kernel/ksysfs.c

/*
 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 */

There's a bunch of other data being printed aside from the usual printable characters. Run it through strings if you want something human readable.

As to what that extra data is... I actually don't know off hand. Let's see if the mailing list has any info...