| Message ID | 20200926191330.96074-2-romain.naour@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [1/2] linux: introduce LINUX_KCFLAGS to add additional options to the C compiler | expand |
On Sat, 26 Sep 2020 21:13:30 +0200 Romain Naour <romain.naour@gmail.com> wrote: > +# https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=5879ab5fafedc8f6f9bfe95a4cf8501b0df90edd > +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97208 > +ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_10)$(BR2_microblaze),yy) > +LINUX_KCFLAGS += -fno-tree-loop-distribute-patterns > +endif I am wondering if this is the right approach. If the -ftree-loop-distribute-patterns breaks stuff for the kernel, presumably it could also break stuff for user-space software. So I guess we should instead disable it entirely in TARGET_CFLAGS. The gotcha being of course that we don't pass TARGET_CFLAGS to the Linux package... Thomas
Hi Thomas, Le 30/09/2020 à 22:59, Thomas Petazzoni a écrit : > On Sat, 26 Sep 2020 21:13:30 +0200 > Romain Naour <romain.naour@gmail.com> wrote: > >> +# https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=5879ab5fafedc8f6f9bfe95a4cf8501b0df90edd >> +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97208 >> +ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_10)$(BR2_microblaze),yy) >> +LINUX_KCFLAGS += -fno-tree-loop-distribute-patterns >> +endif > > I am wondering if this is the right approach. If the > -ftree-loop-distribute-patterns breaks stuff for the kernel, presumably > it could also break stuff for user-space software. So I guess we should > instead disable it entirely in TARGET_CFLAGS. > > The gotcha being of course that we don't pass TARGET_CFLAGS to the > Linux package... Indeed, I have no ideas if the userspace built with this toolchain is really working... except for busybox which was used by qemu_microblazeel_mmu_defconfig Best regards, Romain > > Thomas >
On Wed, 30 Sep 2020 23:04:22 +0200 Romain Naour <romain.naour@gmail.com> wrote: > > The gotcha being of course that we don't pass TARGET_CFLAGS to the > > Linux package... > > Indeed, I have no ideas if the userspace built with this toolchain is really > working... except for busybox which was used by qemu_microblazeel_mmu_defconfig I think we should be passing this flag in TARGET_CFLAGS. What bothers me is that passing it in TARGET_CFLAGS would not resolve the Linux build issue, as Linux isn't built with TARGET_CFLAGS... Thomas
On 01/10/2020 10:06, Thomas Petazzoni wrote: > On Wed, 30 Sep 2020 23:04:22 +0200 > Romain Naour <romain.naour@gmail.com> wrote: > >>> The gotcha being of course that we don't pass TARGET_CFLAGS to the >>> Linux package... >> >> Indeed, I have no ideas if the userspace built with this toolchain is really >> working... except for busybox which was used by qemu_microblazeel_mmu_defconfig > > I think we should be passing this flag in TARGET_CFLAGS. What bothers > me is that passing it in TARGET_CFLAGS would not resolve the Linux > build issue, as Linux isn't built with TARGET_CFLAGS... If it's something needed to "fix the compiler", then it should be in the toolchain wrapper (i.e. TOOLCHAIN_WRAPPER_OPTS). Regards, Arnout
On Tue, 6 Oct 2020 20:46:04 +0200 Arnout Vandecappelle <arnout@mind.be> wrote: > If it's something needed to "fix the compiler", then it should be in the > toolchain wrapper (i.e. TOOLCHAIN_WRAPPER_OPTS). Right, good idea! Romain, do you think you can revisit this using TOOLCHAIN_WRAPPER_OPTS ? Thanks, Thomas
diff --git a/linux/linux.mk b/linux/linux.mk index b9b223e3f3..9ee9054bed 100644 --- a/linux/linux.mk +++ b/linux/linux.mk @@ -158,6 +158,12 @@ ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_8),y) LINUX_KCFLAGS += -Wno-attribute-alias endif +# https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=5879ab5fafedc8f6f9bfe95a4cf8501b0df90edd +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97208 +ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_10)$(BR2_microblaze),yy) +LINUX_KCFLAGS += -fno-tree-loop-distribute-patterns +endif + ifeq ($(BR2_LINUX_KERNEL_DTB_OVERLAY_SUPPORT),y) LINUX_MAKE_ENV += DTC_FLAGS=-@ endif
GCC 10 now enable by default -ftree-loop-distribute-patterns at -O2 or -Os optimization level instead of -O3, see commit [1]. Due to this change, the microblaze kernel doesn't boot (as reported by toolchain-builder project). The gcc docs between version 9 and 10 has been updated accordingly [2] [3] but there no word about this change in the gcc 10 changelog [4]. Fixes microblazebe: https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359536 (glibc) https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359538 (musl) https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359540 (uClubc-ng) Fixes microblazeel: https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359542 (glibc) https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359544 (musl) https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359546 (uClibc-ng) This has been reported upsteam [5]. [1] https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=5879ab5fafedc8f6f9bfe95a4cf8501b0df90edd [2] https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Optimize-Options.html#Optimize-Options [3] https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gcc/Optimize-Options.html#Optimize-Options [4] https://gcc.gnu.org/gcc-10/changes.html [5] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97208 Signed-off-by: Romain Naour <romain.naour@gmail.com> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> --- linux/linux.mk | 6 ++++++ 1 file changed, 6 insertions(+)