Messages in this thread | | | Subject | Re: next/master bisection: baseline.login on rk3288-rock2-square | From | Guillaume Tucker <> | Date | Sat, 6 Feb 2021 13:10:51 +0000 |
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On 05/02/2021 12:05, Ard Biesheuvel wrote: > On Fri, 5 Feb 2021 at 09:21, Ard Biesheuvel <ardb@kernel.org> wrote: >> >> On Thu, 4 Feb 2021 at 22:31, Guillaume Tucker >> <guillaume.tucker@collabora.com> wrote: >>> >>> On 04/02/2021 18:23, Nick Desaulniers wrote: >>>> On Thu, Feb 4, 2021 at 10:12 AM Nathan Chancellor <nathan@kernel.org> wrote: >>>>> >>>>> On Thu, Feb 04, 2021 at 10:06:08AM -0800, 'Nick Desaulniers' via Clang Built Linux wrote: >>>>>> On Thu, Feb 4, 2021 at 8:02 AM Ard Biesheuvel <ardb@kernel.org> wrote: >>>>>>> >>>>>>> On Thu, 4 Feb 2021 at 16:53, Guillaume Tucker >>>>>>> <guillaume.tucker@collabora.com> wrote: >>>>>>>> >>>>>>>> On 04/02/2021 15:42, Ard Biesheuvel wrote: >>>>>>>>> On Thu, 4 Feb 2021 at 12:32, Guillaume Tucker >>>>>>>>> <guillaume.tucker@collabora.com> wrote: >>>>>>>>>> >>>>>>>>>> Essentially: >>>>>>>>>> >>>>>>>>>> make -j18 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- LLVM=1 CC="ccache clang" zImage >>>>>> >>>>>> This command should link with BFD (and assemble with GAS; it's only >>>>>> using clang as the compiler. >>>>> >>>>> I think you missed the 'LLVM=1' before CC="ccache clang". That should >>>>> use all of the LLVM utilities minus the integrated assembler while >>>>> wrapping clang with ccache. >>>> >>>> You're right, I missed `LLVM=1`. Adding `LD=ld.bfd` I think should >>>> permit fallback to BFD. >>> >>> That was close, except we're cross-compiling with GCC for arm. >>> So I've now built a plain next-20210203 (without Ard's fix) using >>> this command line: >>> >>> make LD=arm-linux-gnueabihf-ld.bfd -j18 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- LLVM=1 CC="ccache clang" zImage >>> >>> I'm using a modified Docker image gtucker/kernelci-build-clang-11 >>> with the very latest LLVM 11 and gcc-8-arm-linux-gnueabihf >>> packages added to be able to use the GNU linker. BTW I guess we >>> should enable this kind of hybrid build setup on kernelci.org as >>> well. >>> >>> Full build log + kernel binaries can be found here: >>> >>> https://storage.staging.kernelci.org/gtucker/next-20210203-ard-fix/v5.10-rc4-24722-g58b6c0e507b7-gtucker_single-staging-41/arm/multi_v7_defconfig/clang-11/ >>> >>> And this booted fine, which confirms it's really down to how >>> ld.lld puts together the kernel image. Does it actually solve >>> the debate whether this is an issue to fix in the assembly code >>> or at link time? >>> >>> Full test job details for the record: >>> >>> https://lava.collabora.co.uk/scheduler/job/3176004 >>> >> >> >> So the issue appears to be in the way the linker generates the >> _kernel_bss_size symbol, which obviously has an impact, given that the >> queued fix takes it into account in the cache_clean operation. >> >> On GNU ld, I see >> >> 479: 00065e14 0 NOTYPE GLOBAL DEFAULT ABS _kernel_bss_size >> >> whereas n LLVM ld.lld, I see >> >> 433: c1c86e98 0 NOTYPE GLOBAL DEFAULT ABS _kernel_bss_size >> >> and adding this value may cause the cache clean to operate on unmapped >> addresses, or cause the addition to wrap and not perform a cache clean >> at all. >> >> AFAICT, this also breaks the appended DTB case in LLVM, so this needs >> a separate fix in any case. > > I pushed a combined branch of torvalds/master, rmk/fixes (still > containing my 9052/1 fix) and this patch to my for-kernelci branch > > https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/log/ > > Guillaume, > > It seems there is no Clang-11 coverage there, right? Mind giving this > branch a spin? If this fixes the regressions, we can get these queued > up.
That's right, Clang builds are only enabled on linux-next and mainline at the moment. We could enable it on any other branch where it makes sense. How about just the main defconfig for arm, arm64 and x86_64 on your ardb/for-kernelci branch?
For now I've run another set of builds with clang-11 and got the following test results with your branch on staging:
https://staging.kernelci.org/test/job/ardb/branch/for-kernelci/kernel/v5.11-rc6-146-g923ca344043a/plan/baseline/
which are all passing.
I'll reply to the thread with your patch to confirm.
Guillaume
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