On Tue, Sep 8, 2015 at 7:45 AM, Sedat Dilek <sedat.di...@gmail.com> wrote: > On Tue, Sep 8, 2015 at 12:30 AM, Sedat Dilek <sedat.di...@gmail.com> wrote: >> On Mon, Sep 7, 2015 at 11:20 PM, Sedat Dilek <sedat.di...@gmail.com> wrote: >>> On Mon, Sep 7, 2015 at 10:59 PM, Linus Torvalds >>> <torva...@linux-foundation.org> wrote: >>>> On Mon, Sep 7, 2015 at 1:53 PM, Sedat Dilek <sedat.di...@gmail.com> wrote: >>>>> >>>>> That does not work. >>>> >>>> .. because you didn't do what I told you to do. >>>> >>>>> I copied a gcc-compiled percpu.o OR deleted/renamed percpu.o and >>>>> re-invoked make - this starts a complete new build from scratch. >>>> >>>> Right. Because you changed the compiler name, so now the build system >>>> realizes that the old build instructions are stale. >>>> >>>> Which is why you have to: >>>> >>>>>> Use a wrapper around the compiler (and point to that wrapper with the >>>>>> "to switch compilers from under the make, without the build paths >>>>>> changing (because otherwise our makefile auto-machinery notices that >>>>>> flags and command changed). >>>>>> >>>>>> Use CC (or CROSS_COMPILE) to point at your wrapper. >>>>> >>>>> No idea how to realize that, sorry. >>>> >>>> Literally just do something like this: >>>> >>>> - have a shell script call "mycompiler" and make it do gcc/llvm "$@". >>>> >>>> - or even just use a symlink (the script has the advantage that you >>>> can play with the options etc too) >>>> >>>> - change the shell script (or symlink) itself, and make sure to use >>>> the same CC for "make" at all times, so that the build script never >>>> sees that the underlying command is now different. >>>> >>>> It should work fine, I've done it a couple of times (although >>>> admittedly not recently) >>>> >>> >>> OK, I have created a mycompiler shell-script and use that for CC and >>> HOSTCC in my own build-script. >>> >>> Using CLANG... >>> >>> [ /usr/bin/mycompiler ] >>> >>> #!/bin/bash >>> >>> clang "$@" >>> - EOF - >>> >>> $ mycompiler --version >>> clang version 3.7.0 (tags/RELEASE_370/final) >>> Target: x86_64-unknown-linux-gnu >>> Thread model: posix >>> >>> Switching to GCC... >>> >>> [ /usr/bin/mycompiler ] >>> >>> #!/bin/bash >>> >>> gcc-4.9 "$@" >>> - EOF - >>> >>> $ mycompiler --version >>> gcc-4.9 (Ubuntu 4.9.2-0ubuntu1~12.04) 4.9.2 >>> Copyright (C) 2014 Free Software Foundation, Inc. >>> This is free software; see the source for copying conditions. There is NO >>> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. >>> >>> Thanks, that helped me a lot. >>> >> >> Sadly, this trick does not work here with Linux v4.2. >> > > So, the problem is any change to your make-lines. > Means $COMPILER and/or compiler flags! > > I simplified in Makefile... > > COMPILER := clang > export COMPILER > > and then did a symlink gcc-4.9 -> clang. > > This did NOT work because clang uses a compiler-flag > '-no-integrated-as' which does not exist for gcc! > > So, switching from gcc -> clang or vice-versa is not possible with > your compiler-wrapper-script trick :-(. > > Anyway, I need a different solution. > > One of my ideas was to hack the mm/Makefile. > > --- a/mm/Makefile > +++ b/mm/Makefile > @@ -2,6 +2,9 @@ > # Makefile for the linux memory manager. > # > > +COMPILER := gcc > +export COMPILER > + > KASAN_SANITIZE_slab_common.o := n > KASAN_SANITIZE_slub.o := n > > @@ -78,3 +81,6 @@ obj-$(CONFIG_CMA) += cma.o > obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o > obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o > obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o > + > +COMPILER := clang > +export COMPILER > > Not sure if this works. >
This does not work. And if it had worked - it cannot due to passing invalid compiler-flags to gcc. Empty head. - Sedat - -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/