Like built-in.a, the command length of the *.mod rule scales with
the depth of the directory times the number of objects in the Makefile.
Add $(obj)/ by the shell command (awk) instead of by Make's builtin
function.
In-tree modules still have some room to the limit (ARG_MAX=2097152),
but this is more future-proof for big modules in a deep directory.
For example, you can build i915 as a module (CONFIG_DRM_I915=m) and
compare drivers/gpu/drm/i915/.i915.mod.cmd with/without this commit.
The issue is more critical for external modules because the M= path
can be very long as Jeff Johnson reported before [1].
[1] https://lore.kernel.org/linux-kbuild/[email protected]/
Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>
Tested-by: Sedat Dilek <[email protected]> # LLVM-14 (x86-64)
Masahiro Yamada
c6031b1dbb