Messages in this thread | | | Date | Mon, 7 Sep 2015 23:20:08 +0200 | Subject | Re: Use (two) different compilers at build-time? | From | Sedat Dilek <> |
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On Mon, Sep 7, 2015 at 10:59 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > On Mon, Sep 7, 2015 at 1:53 PM, Sedat Dilek <sedat.dilek@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.
- Sedat -
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