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

Felix Fietkau nbd at openwrt.org
Fri Oct 30 09:16:10 EDT 2015

On 2015-10-30 13:54, Toke Høiland-Jørgensen wrote:
> Felix Fietkau <nbd at openwrt.org> writes:
>> How is this more useful than simply checking a hash of the kernel
>> module in /lib/modules and comparing that with the corresponding file
>> on the host?
> Because the value in /sys/module/ is from the *loaded* module. So it
> catches the case where the module file is updated but not reloaded (was
> bitten by this a couple of times).
> Also, you can put the module source git hash as the build id, so it can
> be referred back to the source, rather than the compiled file.
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?
You could just make a simple wrapper script that reinstalls and reloads
your module and complains if reloading fails.

When I do wifi driver development, I have to reload a chain of modules
frequently. Since this is tedious and error prone, I have a script that
simply pulls the latest package from my laptop via HTTP, unloads all
relevant modules, then reloads them.

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?

- Felix
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