Re: Kernel Cross Compiling

[Herbert Poetzl <herbert@13thfloor.at>]

On Sat, Feb 14, 2004 at 12:32:07AM -0800, Timothy D. Witham wrote:
>  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.

thanks, yes, I knew about that, but the thing is, I would
like to use this as automated test (well first step of
an automated test) for linux-vserver[1] development, and 
for that purpose i386/ia64 and ppc/ppc64 is a good start 
but not nearly sufficient, we currently 'support' (or at
least try to ;) the following archs:

  alpha, i386, ia64, mips/64, hppa/64, ppc/64
  sparc/64, s390/x, x86_64, uml

and got an officially assigned syscall number for 

  i386, s390, sparc/64, sh3/4, x86_64

but if you are interested in extending this and making
it available for linux-vserver kernel compile tests
too, I'm willing to help if I can ...

TIA,
Herbert

> 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/
> >    	
> > 
> > -
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> -- 
> Timothy D. Witham - Lab Director - wookie@osdl.org
> Open Source Development Lab Inc - A non-profit corporation
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