[OpenWrt-Devel] [PATCH] Allow kernel modules to keep build ID debug symbol.

Toke Høiland-Jørgensen toke at toke.dk
Fri Oct 30 09:37:05 EDT 2015


Felix Fietkau <nbd at openwrt.org> writes:

> I'm still not convinced that this is very useful - if you have issues
> that you sometimes reinstall modules, but don't reload them and have
> to check the id, why not just fix your workflow instead?

I did script it, but I'm trying to have a way to make this available to
others as well. Let me give a bit more context:

I'm using this for the 'cake' shaper module, which is built out-of-tree
as kmod-sched-cake, available in the ceropackages feed. Other people are
testing this, with their own builds; and I want to be able to keep track
of which versions they are testing with, without having to impose a
specific workflow for them: With this change, I can just add the
build-id linker option in the package Makefile, and it will be available
on the router running the code, where it can be automatically extracted
by the Flent tool as part of the test.

> Either way, if this is really necessary for you, I'm okay with adding
> support for keeping the build-id, but setting this in the package
> makefile (especially in the Build/Exports section) seems rather quirky
> to me. Since this is a rather exotic debugging-only feature, why not
> just add a global config option for it?

Well I was trying to find a way to make it possible to set this for one
module (package) only, in order to keep the impact as low as possible.
And this was the only I could figure out to make it work (since the
RSTRIP variable in rules.mk seems to be expanded before the contents of
the package Makefile, so I can't add a variable there).

But since this requires a specific kernel configuration anyway
(CONFIG_KALLSYMS), global config changes are needed anyway, so am fine
with making it a global switch. Can resubmit is as such.

Should I just add a new switch under "Global build settings"? Or would
it be okay to condition it on CONFIG_KERNEL_KALLSYMS (which it needs to
work anyway)?

Incidentally, is there a way to depend on these options from the package
Makefile?

-Toke
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