Messages in this thread Patch in this message | | | Date | Wed, 7 Jan 2009 14:23:37 +0100 | From | Sam Ravnborg <> | Subject | Re: [REGRESSION] Recent change to kernel spikes out ccache/distcc |
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On Wed, Jan 07, 2009 at 12:35:09PM +0000, Jan Beulich wrote: > >>> Sam Ravnborg <sam@ravnborg.org> 07.01.09 12:31 >>> > >What is the gain/pain ratio here? > > Certainly depends on the pov - it reduces the kernel module (disk) image > sizes quite a bit, so from a distro perspective its a move against the ever > growing package sizes (and the disk space) hundreds or even thousands > of modules require.
The kernel modules seldom export anything so the benefit is minimal here.
I really think we are on a wrong track here.
I did a 15 minutes hack to try ripping the .c -> .s -> .o stuff out.
diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 5d90030..8c93dc3 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -153,7 +153,7 @@ $(obj)/%.i: $(src)/%.c FORCE cmd_genksyms = \ $(CPP) -D__GENKSYMS__ $(c_flags) $< | \ - $(GENKSYMS) -T $@ -A -a $(ARCH) \ + $(GENKSYMS) -T $@ $(if $(CONFIG_KBUILD_STRIP_CRC), -A) -a $(ARCH) \ $(if $(KBUILD_PRESERVE),-p) \ $(if $(1),-r $(firstword $(wildcard $(@:.symtypes=.symref) /dev/null))) @@ -192,6 +192,7 @@ v_file = $(@D)/.tmp_$(@F:.o=.v) tmp_o_file = $(@D)/.tmp_$(@F) no_g_c_flags = $(filter-out -g%,$(c_flags)) +ifdef CONFIG_KBUILD_STRIP_CRC cmd_cc_o_c = $(CC) $(c_flags) -S -o $(s_file) $< cmd_modversions = \ @@ -208,8 +209,20 @@ cmd_modversions = \ fi; \ else \ rm -f $(v_file); \ - $(CC) $(no_g_c_flags) -c -o $@ $(s_file); \ + $(CC) $(no_g_c_flags) -c -o $@ $< ; \ fi; +else +cmd_cc_o_c = $(CC) $(c_flags) -c -o $(tmp_o_file) $< + +cmd_modversions = \ + if $(OBJDUMP) -h $(tmp_o_file) | grep -q __ksymtab; then \ + $(call cmd_genksyms, $(KBUILD_SYMTYPES)) > $(v_file); \ + $(LD) $(LDFLAGS) -r -o $@ $(tmp_o_file) -T $(v_file); \ + else \ + rm -f $(v_file); \ + fi; + +endif endif ifdef CONFIG_FTRACE_MCOUNT_RECORD
Jan - I need some hard numbers to convince me that stripping the __crc symbols is worth it.
We can make it a configuration option as I showed above but we should at least know what we are gaining for this.
I am very positive about stripping of the modules in general, but the __crc_ symbols seems to trigger a few things: 1) ccahce, distcc issues in the MODVERSION case (that is allmodconfig builds) 2) It does not increase readability of the Makefile machinery and I like more people to be able to hack on this - not less.
Thanks, Sam
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