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

Felix Fietkau nbd at openwrt.org
Fri Oct 30 08:51:00 EDT 2015

On 2015-10-30 11:44, Toke Høiland-Jørgensen wrote:
> This change adds support for specifying that a particular kernel module
> wants to keep its build ID debug symbol (.note.gnu.build-id). This
> symbol is exported in sysfs by the kernel (if the kernel is compiled
> with CONFIG_KALLSYMS) and so can be used to uniquely identify a version
> of a kernel module in a running kernel (if the module is built with
> suitable linker options). This is useful for keeping track of different
> versions of a module when doing experiments and development.
> A kernel module Makefile can specify that the build ID should be kept by
> exporting PKG_KEEP_BUILD_ID in the Build/Exports section. This will add
> ~100 bytes to the size of the .ko (depending on the length of the build
> ID specified).
> The default is to strip the build ID (as before), so there is no size
> difference for kernel modules that do not export this variable.
> Signed-off-by: Toke Høiland-Jørgensen <toke at toke.dk>
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?

- Felix
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