On Sat, Feb 1, 2025 at 6:33 AM Charlie Jenkins <charlie@xxxxxxxxxxxx> wrote: > > On Sat, Feb 01, 2025 at 12:10:02AM +0900, Masahiro Yamada wrote: > > On Fri, Jan 31, 2025 at 3:54 PM Charlie Jenkins <charlie@xxxxxxxxxxxx> wrote: > > > > > > On Thu, Jan 30, 2025 at 08:52:45PM -0700, Nathan Chancellor wrote: > > > > On Wed, Jan 22, 2025 at 07:17:26PM -0800, Charlie Jenkins wrote: > > > > > On riscv, kernel modules end up with a significant number of local > > > > > symbols. This becomes apparent when compiling modules with debug symbols > > > > > enabled. Using amdgpu.ko as an example of a large module, on riscv the > > > > > size is 754MB (no stripping), 53MB (--strip-debug), and 21MB > > > > > (--strip-unneeded). ON x86, amdgpu.ko is 482MB (no stripping), 21MB > > > > > (--strip-debug), and 20MB (--strip-unneeded). > > > > > > > > > > Use --strip-unneeded instead of --strip-debug to strip modules so > > > > > decrease the size of the resulting modules. This is particularly > > > > > relevant for riscv, but also marginally aids other architectures. > > > > > > > > > > Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx> > > > > > > > > Is there any sort of regression risk with this patch? If so, another > > > > option may be to give another level to INSTALL_MOD_STRIP like 2 so that > > > > INSTALL_MOD_STRIP=1 continues to behave as before but people can easily > > > > opt into this option. No strong opinion because I am not sure but was > > > > not sure if it was considered. > > > > > > I do not believe this would cause regressions. The description on gnu > > > strip is: > > > > > > "Remove all symbols that are not needed for relocation processing in > > > addition to debugging symbols and sections stripped by --strip-debug." > > > > > > The description on llvm-strip is: > > > > > > "Remove from the output all local or undefined symbols that are not > > > required by relocations. Also remove all debug sections." > > > > > > gnu strip --strip-unneeded strips slightly more aggressively but it does > > > not appear this causes any issues. > > > > > > > > > > > Regardless: > > > > > > > > Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx> > > > > > > Thanks! > > > > > > > > > It is true --strip-unneeded drops a lot of compiler-generated symbols, but > > it also drops real symbols that originate in the source code. > > > > So, this would give user-visible changes for kallsyms at least. > > Adding INSTALL_MOD_STRIP="--strip-unneeded" would be sufficient for > riscv. However, this has the downside that riscv will require different > flags than other architectures to get reasonably sized modules. You can use INSTALL_MOD_STRIP=--strip-unneeded for all architecture if you like. I assume this is a riscv issue. Specifically, riscv gcc. With LLVM=1, I see much smaller riscv modules using INSTALL_MOD_STRIP=1. --strip-unneeded is needlessly aggressive for other architectures, and I do not see a good reason to change the default. > > I believe these symbols are only useful for debugging, is there a > usecase for them to be available when the user has modules compiled with > INSTALL_MOD_STRIP=1? > > - Charlie > > > > > > > $ riscv64-linux-gnu-nm -n > > /tmp/strip-unneeded/lib/modules/6.13.0-09760-g69e858e0b8b2/kernel/drivers/gpu/drm/amd/amdgpu/amdgpu.ko > > > /tmp/symbol-with-strip-unneeded > > $ riscv64-linux-gnu-nm -n > > /tmp/strip-debug/lib/modules/6.13.0-09760-g69e858e0b8b2/kernel/drivers/gpu/drm/amd/amdgpu/amdgpu.ko > > > /tmp/symbol-with-strip-debug > > > > $ diff -u /tmp/symbol-with-strip-debug /tmp/symbol-with-strip-unneeded > > [ snip ] > > 00000000001676cc t uvd_v6_0_ring_test_ring > > 0000000000167802 t uvd_v6_0_ring_emit_pipeline_sync > > 0000000000167a02 t uvd_v6_0_ring_emit_fence > > -0000000000167b58 r CSWTCH.2 > > -0000000000167b68 r abm_settings > > -0000000000167b80 r abm_config > > -0000000000167b90 r min_reduction_table_v_2_2 > > -0000000000167ba0 r max_reduction_table_v_2_2 > > -0000000000167bb0 r min_reduction_table > > -0000000000167bc0 r max_reduction_table > > -0000000000167bd0 r custom_backlight_curve0 > > 0000000000167c38 r abm_settings_config2 > > 0000000000167c70 r abm_settings_config1 > > 0000000000167ca8 r abm_settings_config0 > > > > > > > > > > -- > > Best Regards > > Masahiro Yamada -- Best Regards Masahiro Yamada
