On Thu, Jan 28, 2021 at 12:46 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote: > > [ LLVM ] > > Today, I switched over to LLVM version 12.0.0-rc1. > > > [ Step #1: 5.11.0-rc5-5-amd64-clang12-pgo ] > > My first kernel was built with CONFIG_PGO_CLANG=y and LLVM=1 plus LLVM_IAS=1. > > [ start-build_5.11.0-rc5-5-amd64-clang12-pgo.txt ] > dileks 193090 193065 0 06:54 pts/2 00:00:00 /usr/bin/perf_5.10 > stat make V=1 -j4 HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang > LD=ld.lld LLVM=1 LLVM_IAS=1 PAHOLE=/opt/pahole/bin/pahole > LOCALVERSION=-5-amd64-clang12-pgo KBUILD_VERBOSE=1 > KBUILD_BUILD_HOST=iniza KBUILD_BUILD_USER=sedat.dilek@xxxxxxxxx > KBUILD_BUILD_TIMESTAMP=2021-01-28 bindeb-pkg > KDEB_PKGVERSION=5.11.0~rc5-5~bullseye+dileks1 > > Config: config-5.11.0-rc5-5-amd64-clang12-pgo > > > [ Step #2: x86-64 defconfig & vmlinux.profdata ] > > Booted into 5.11.0-rc5-5-amd64-clang12-pgo and built an x86-64 > defconfig to generate/merge a vmlinux.profdata file. > > [ start-build_x86-64-defconfig.txt ] > dileks 18430 15640 0 11:15 pts/2 00:00:00 make V=1 -j4 > HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang LD=ld.lld LLVM=1 > LLVM_IAS=1 > > Script: profile_clang-pgo.sh > Config: dot-config.x86-64-defconfig > > > [ Step #3.1: 5.11.0-rc5-6-amd64-clang12-pgo & GNU-AS ] > > The first rebuild with CONFIG_PGO_CLANG=n and "LLVM=1 > KCFLAGS=-fprofile-use=vmlinux.profdata". > I was able to boot into this one. > Used assembler: GNU-AS 2.35.1 > > [ start-build_5.11.0-rc5-6-amd64-clang12-pgo.txt ] > dileks 65734 65709 0 11:54 pts/2 00:00:00 /usr/bin/perf_5.10 > stat make V=1 -j4 HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang > LD=ld.lld PAHOLE=/opt/pahole/bin/pahole > LOCALVERSION=-6-amd64-clang12-pgo KBUILD_VERBOSE=1 > KBUILD_BUILD_HOST=iniza KBUILD_BUILD_USER=sedat.dilek@xxxxxxxxx > KBUILD_BUILD_TIMESTAMP=2021-01-28 bindeb-pkg > KDEB_PKGVERSION=5.11.0~rc5-6~bullseye+dileks1 LLVM=1 > KCFLAGS=-fprofile-use=vmlinux.profdata > > Config: config-5.11.0-rc5-6-amd64-clang12-pgo > > > [ Step #3.2: 5.11.0-rc5-7-amd64-clang12-pgo & Clang-IAS ] > > The second rebuild with CONFIG_PGO_CLANG=n and "LLVM=1 > KCFLAGS=-fprofile-use=vmlinux.profdata" plus LLVM_IAS=1. > Compilable but NOT bootable in QEMU and on bare metal. > Used assembler: Clang-IAS v12.0.0-rc1 > > [ start-build_5.11.0-rc5-7-amd64-clang12-pgo.txt ] > dileks 6545 6520 0 16:31 pts/2 00:00:00 /usr/bin/perf_5.10 > stat make V=1 -j4 HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang > LD=ld.lld PAHOLE=/opt/pahole/bin/pahole > LOCALVERSION=-7-amd64-clang12-pgo KBUILD_VERBOSE=1 > KBUILD_BUILD_HOST=iniza KBUILD_BUILD_USER=sedat.dilek@xxxxxxxxx > KBUILD_BUILD_TIMESTAMP=2021-01-28 bindeb-pkg > KDEB_PKGVERSION=5.11.0~rc5-7~bullseye+dileks1 LLVM=1 > KCFLAGS=-fprofile-use=vmlinux.profdata LLVM_IAS=1 > > Config: config-5.11.0-rc5-7-amd64-clang12-pgo > > > [ Conclusion ] > > The only statement I can tell you is a "PGO optimized" rebuild with > LLVM_IAS=1 is compilable but NOT bootable. Thanks for the extensive testing and report. Can you compress, upload, and post a link to your kernel image? I would like to take it for a spin in QEMU and see if I can find what it's doing, then work backwards from there. -- Thanks, ~Nick Desaulniers
