Re: [XenARM] initial bootstrap code

["George G. Davis" <gdavis@xxxxxxxxxx>]

On Wed, Oct 17, 2007 at 08:47:13PM -0400, George G. Davis wrote:
> Hello Damien,
> 
> On Wed, Oct 17, 2007 at 04:53:39PM -0400, Damien Barthélémy wrote:
> > Hello
> > 
> > This is my first message on the list. I am the student working with Daniel
> > Rossier.
> > 
> > We finally got a minimal xen code (without virt mechanisms, bootstrap only)
> > building, linking and starting.
> > 
> > The first step was to get a minimal version of linux 2.6.18 (isolate the
> > linux arm bootstrap). We built only some files in /arch/arm and got a 3 ko
> > linux image. We suppressed the directories containing unused code /fs /crypt
> > /kernel /drivers /mm /ipc /net...
> > 
> > The initial idea was to introduce this bootstrap in the xen 3.1 tree. But I
> > got many problems with this job. It is difficult to adapt the xen Makefiles
> > to get the linux bootstrap build. I had problems with CFLAGS, linker script,
> > the whole build process, ... We decided not to spend to much (more) time on
> > this problem and to include the xen tree into our modified linux bootstrap
> > tree. The linux bootstrap code call the xen first C function (start_xen).
> 
> FWIW, I'ld recommend using a .config and config.h generated for the
> Xen ARM target machine using Linux.  Have xen/arch/arm/Rules.mk
> include the .config and include config.h in source files to properly
> select ARM processor and machine build time options.  I'ld also recommend
> using (a sub set of ) the linux/arch/arm/Makefile as the basis for the
> xen/arch/arm/Rules.mk file.  In this way you should have most of the
> compiler machine dependent options properly specified and then sources
> leveraged from Linux for Xen ARM will select all of the proper ARM
> processor and machine specific code.  Unfortunately Xen arch and machine
> selection is much more primitive (non-existent even : ) than Linux kbuild
> but using the preceding helps to alleviate this issue (especially for
> ARM which does not have a common machine architecture as do x86 and other
> architectures).  It would be nice to augment Xen ARM processor and
> machine selection via some type of `make *config` option similar to
> Linux but, as I mention, the preceding should be good enough to get
> started...
> 
> > 
> > This code is now avaible on sourceforge
> > http://sourceforge.net/projects/embeddedxen/

I had a quick look at the tarball, interesting approach integrating Xen
source as a subdirectory of Linux-2.6.18.  : )  Now I see how that solved
the problem of gcc/gas command line args as well as the problem of
configuring the ARM machine (using Linux kbuild : ).  Could do similar
as I mentioned above but that leaves the machine config issue unresolved
and I reckon it is rather inconvenient to create config files under
Linux and manually copy those into Xen.  I do like your approach so
far but it will need to be reconciled when pushing it back upstream...

-- 
Regards,
George

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