Re: [PATCH v2] lib{fdt,elf}: move lib{fdt,elf}-temp.o and their deps to $(targets)

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Mon, Jan 22, 2024 at 12:39:55PM +0100, Michal Orzel wrote:
> At the moment, trying to run xencov read/reset (calling SYSCTL_coverage_op
> under the hood) results in a crash. This is due to a profiler trying to
> access data in the .init.* sections (libfdt for Arm and libelf for x86)
> that are stripped after boot. Normally, the build system compiles any
> *.init.o file without COV_FLAGS. However, these two libraries are
> handled differently as sections will be renamed to init after linking.
> 
> To override COV_FLAGS to empty for these libraries, lib{fdt,elf}.o were
> added to nocov-y. This worked until e321576f4047 ("xen/build: start using
> if_changed") that added lib{fdt,elf}-temp.o and their deps to extra-y.
> This way, even though these objects appear as prerequisites of
> lib{fdt,elf}.o and the settings should propagate to them, make can also
> build them as a prerequisite of __build, in which case COV_FLAGS would
> still have the unwanted flags. Fix it by switching to $(targets) instead.
> 
> Also, for libfdt, append libfdt.o to nocov-y only if CONFIG_OVERLAY_DTB
> is not set. Otherwise, there is no section renaming and we should be able
> to run the coverage.
> 
> Fixes: e321576f4047 ("xen/build: start using if_changed")
> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>

Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

Thanks,

-- 
Anthony PERARD