On 21.04.2018 04:38, Nicholas Piggin wrote: > On Fri, 20 Apr 2018 19:46:08 -0400 > John David Anglin <dave.anglin@xxxxxxxx> wrote: > >> On 2018-04-20 9:20 AM, James Bottomley wrote: >>> On Fri, 2018-04-20 at 23:07 +1000, Nicholas Piggin wrote: >>>> Does parisc still need to use -ffunction-sections flag, now that we >>>> build with thin archives and don't use `ld -r`? I think it should not >>>> be required anymore. >>> I think we may have some modules that are too big. The original >>> problem is that without -ffunction-sections, the linker doesn't have >>> any way of inserting trampolines in the middle of the text code, and >>> our relative jumps are comparatively short distance, so to get from the >>> code to the PLT is sometimes to far for a single relative jump. >> Correct. This is not just an issue with `ld -r`. >> >> The -ffunction-sections flag is only helpful for 32-bit PA 1.x builds. >> PA 2.0 `b,l` branches >> are 32 times longer and it's unlikely the maximum module size is >> exceeded in a 32-bit build. >> >> The 64-bit linker doesn't support adding long branch stubs. This limits >> the maximum kernel >> size to about 8 MB using without using long calls. They are slow. >> >> I would keep this option for PA 1.x builds. > > Well I'm interested. Would you really have a single .c/.S file that > benefits from it? It's possible. gnu ld has a --stats option, for > powerpc it gives you an output like: > > powerpc64le-linux-gnu-ld: linker stubs in 0 groups > powerpc64le-linux-gnu-ld: branch 0 > powerpc64le-linux-gnu-ld: toc adjust 0 > powerpc64le-linux-gnu-ld: long branch 0 > powerpc64le-linux-gnu-ld: long toc adj 0 > powerpc64le-linux-gnu-ld: plt call 0 > powerpc64le-linux-gnu-ld: plt call toc 0 > powerpc64le-linux-gnu-ld: global entry 0 > powerpc64le-linux-gnu-ld: total time in link: 0.242010 > > Not sure if parisc has the same output, but if it does, add --stats to > LDFLAGS_vmlinux, and you could see what happens with/without > -ffunction-sections. That's all I get on parisc: hppa-linux-gnu-ld: total time in link: 0.409295 hppa-linux-gnu-ld: data size 43970560 Helge -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
