[llvmlinux] percpu | bitmap issue? (Cannot boot on bare metal due to a kernel NULL pointer dereference)

Sedat Dilek sedat.dilek at gmail.com
Mon Sep 14 09:55:52 UTC 2015

On Mon, Sep 14, 2015 at 11:35 AM, Ingo Molnar <mingo at kernel.org> wrote:
> * Peter Zijlstra <peterz at infradead.org> wrote:
>> > I invite you to join the discussion at LLVMLinux... As I know... "YES, you
>> > can." Linux x86/x86_64 (assembler) Kung-Fu. ( I admit I have not these skillz.
>> > )
>> Its a matter of time for me; I simply do not have enough time as it is so I have
>> to make choices.
> We are also willing to apply clean, sensible patches.
> Alas that collection of llvm patches quoted in this thread:
>   30 files changed, 188 insertions(+), 161 deletions(-)
> had quite a few objectionable hacks in them.

AFAICS LLVMLinux is still a work-in-progress project.

Three patches are labeled with "DO-NOT-UPSTREAM"...

      DO-NOT-UPSTREAM scsi, osd, LLVMLinux: Remove __weak attribute
      WORKAROUND DO-NOT-UPSTREAM x86, boot: Work around clang PR18415.
      DO-NOT-UPSTREAM xen, LLVMLinux: Remove VLAIS from xen mmu

I cannot say much to the other patches - what status they have -
"reported to BTS and have no feedback" or "still discussed" or

Some bug-reports are very old - especially in the LLLVM and CLANG BTS.

Can you be concrete on the patches which have in your eyes "a few
objectionable hacks in"?

>From my side... How can the correbolation be improved...?

Linux kernel development <-> LLVMLinux development <-> LLVM/CLANG development

BTW, LLVMLinux is a project hosted at Linux Foundation.

I also remember the interview with Linus and c't magazine (German, I
bought this edition) where he talks about compiler and especially
using LLVM for compiling a Linux-kernel.

If you look at the git-logs, there are people found bugs using
LLVM/CLANG and fixed them.
Personally, I like the "verbose" output of LLVM/CLANG more than GCC v4.9.
I did not try any GCC v5.x.


- Sedat -

[1] http://www.heise.de/ct/ausgabe/2014-25-Linus-Torvalds-im-Interview-2449660.html

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