Re: Kernel Cross Compiling

[Timothy D. Witham]

 Just to point out that we (OSDL) already do this.

http://www.osdl.org/projects/26lnxstblztn/results/


  We are willing to add more but it is always willing
to look at adding more.

Tim

On Fri, 2004-02-13 at 12:57, Herbert Poetzl wrote:
> Hi Folks!
> 
> I'm currently investigating the requirements/doability
> of a kernel cross compiling test bed/setup, able to do
> automated kernel builds for different architecture,
> just to see if it compiles and later to verify if a 
> given patch breaks that compile on any of the tested
> archs ...
> 
> here a short status, and some issues I ran into so far,
> some of them with solutions, others without, and some
> interesting? observations ...
> 
> I would be happy if somebody who has done similar, or
> knows how to do it properly ;) could comment on that,
> and/or point out possible improvements ...
> 
> TIA,
> Herbert
> 
> 
> 1) CROSS COMPILER / TOOLCHAIN
> 
>    after reading and testing several cross build and
>    toolchain building howtos, I decided to do it a little 
>    different, because I do not need glibc to compile the 
>    kernel ...
> 
>    the result are two .spec files[1], or the commands 
>    used to build an appropriate toolchain ...
>    
>    for the binutils the required commands are:
> 
>    	configure  	    	    	    	    	\
> 		--disable-nls                           \
> 		--prefix=/usr                           \
> 		--mandir=/usr/share/man                 \
> 		--infodir=/usr/share/info               \
> 		--target=${CROSS_ARCH}-linux
>    	make
>    
>    and for the gcc (after the binutils have been
>    installed on the host):
> 
>    	configure  	    	    	    	    	\
> 		--enable-languages=c			\
>         	--disable-nls                           \
> 		--disable-threads			\
> 		--disable-shared			\
> 		--disable-checking			\
>         	--prefix=/usr                           \
>         	--mandir=/usr/share/man                 \
>         	--infodir=/usr/share/info               \
>         	--target=${CROSS_ARCH}-linux
>    	make  TARGET_LIBGCC2_CFLAGS='-Dinhibit_libc  \
> 		-D__gthr_posix_h'
>    
>    where ${CROSS_ARCH} is the target architecture you want
>    to compile the toochain for, in my case, this where one
>    of the following:
> 
>    	alpha, hppa, hppa64, i386, ia64, m68k, mips, 
> 	mips64, ppc, ppc64, s390, sparc, sparc64, x86_64
> 
>   PROBLEMS HERE:
> 
>    I decided to use binutils 2.14.90.0.8, and gcc 3.3.2,
>    but soon discovered that gcc-3.3.2 will not be able 
>    to build a cross compiler for some archs like the
>    alpha, ia64, powerpc and even i386 ;) without some
>    modifications[2] but with some help, I got all headers
>    fixed, except for the ia64, which still doesn't work
> 
> 
> 2) KERNEL CROSS COMPILING
> 
>    equipped with the cross compiling toolchains for all
>    but one of the architectures mentioned above, I wrote
>    a little script, which basically does nothing else 
>    but compiling a given kernel for all possible archs.
> 
>    basically this can be accomplished by doing:
> 
> 	make ARCH=<arch> CROSS_COMPILE=<arch>-linux-
> 
> 
>    the first result was harrowing:
> 
> 				2.4.25-pre  2.6.2-rc
>    ----------------------------------------------------
> 	[ARCH alpha/alpha]      succeeded.  succeeded.
> 	[ARCH hppa/parisc]      failed.     failed.
> 	[ARCH hppa64/parisc]    failed.     failed.
> 	[ARCH i386/i386]        succeeded.  succeeded.
> 	[ARCH m68k/m68k]        failed.     failed.
> 	[ARCH mips/mips]        failed.     failed.
> 	[ARCH mips64/mips]      failed.     failed.
> 	[ARCH ppc/ppc]          succeeded.  succeeded.
> 	[ARCH ppc64/ppc64]      failed.     failed.
> 	[ARCH s390/s390]        failed.     failed.
> 	[ARCH sparc/sparc]      failed.     succeeded.
> 	[ARCH sparc64/sparc]    failed.     failed.
> 	[ARCH x86_64/x86_64]    failed.     succeeded.
> 
>    so only alpha, i386 and ppc did work on the first run.
> 
>    what I discovered was, that there IS a big difference
>    between an empty .config file and a non exististing 
>    one, where latter allowed the make oldconfig to work
>    similar to the make defaultconfig available on 2.6,
>    and added some archs (see [3] for details)
> 
>   PROBLEMS & SOLUTIONS HERE:
> 
>    ppc64: 
> 	CROSS32_COMPILE=ppc-linux-  
> 	is needed to make this work as expected.
> 
>    hppa/hppa64: 
> 	seems not to compile without using a very big
> 	patch, which changes a lot inside the kernel
> 
>    mips/mips64:
> 	seem to use the 'obsoleted' -mcpu= option
> 	which results in a cc1: error: invalid option 
> 	`cpu=<cpu-here>'
> 
>    m68k:
> 	fails with a hundred errors in the includes
> 
> 
> 3) CONCLUSIONS
> 
>    it seems that recent kernels (2.4 and 2.6) do not support
>    most of the architectures they contain without heavy
>    patching (haven't tested for arm, sh3/4, ...)
> 
>    building cross compiler toolchains isn't that often done
>    otherwise it would not require such modifications, and
>    the documentation would be up to date ...
> 
>    it seems that with some minor patches and kernel tweaks
>    an automated build is in reach, although some archs seem
>    to break from one release to the other ...
> 
>    the non mainline branches, if they exist are some kernel
>    versions behind the current mainstream kernel, which 
>    might not mean anything ...
> 
> 
> 4) LINKS & REFERENCES
> 
>    [1]	http://vserver.13thfloor.at/Stuff/Cross/binutils-cross.spec
> 	http://vserver.13thfloor.at/Stuff/Cross/gcc-cross.spec
> 
>    [2]  http://vserver.13thfloor.at/Stuff/Cross/
> 		gcc-3.3.2-cross-alpha-fix.diff.bz2
> 		gcc-3.3.2-cross-i386-fix.diff.bz2
> 		gcc-3.3.2-cross-ia64-fix.diff.bz2
> 		gcc-3.3.2-cross-powerpc-fix.diff.bz2
> 
>    [3]  http://vserver.13thfloor.at/Stuff/Cross/compile.info
> 
>    ia64:	http://www.gelato.unsw.edu.au/kerncomp/
>    mips:	http://www.linux-mips.org/kernel.html
>    hppa:	http://www.parisc-linux.org/kernel/index.html
>    ppc64:	http://linuxppc64.org/
>    	
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-gcc" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
-- 
Timothy D. Witham - Lab Director - wookie@xxxxxxxx
Open Source Development Lab Inc - A non-profit corporation
12725 SW Millikan Way - Suite 400 - Beaverton OR, 97005
(503)-626-2455 x11 (office)    (503)-702-2871     (cell)
(503)-626-2436     (fax)

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/