RE: [Xen-devel] linux/arch/xen/i386 or linux/arch/i386/xen

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

Um, one other minor semantic issue.  The semantics of
using mach-xxx may be inappropriate.  If my understanding
is correct, two mach-xxx's cannot both be built, e.g. one
cannot build a kernel which supports (for i386) both
mach-es7000 and mach-voyager.

There have been various discussions on this list about
"transparent paravirtualization", i.e. the ability for
a paravirtualized kernel to run both as a guest of Xen
and on bare metal.  This is definitely an objective of
Xen/ia64.  Nobody has tried it for Xen/x86, but if it
can be done, I'm sure commercial companies and distros
would be eager to utilize it (one less set of bits to
support).

In many ways, a "xen" subdirectory is much more like
a "pci" or "math-emu" subdirectory, than a subarch.
For example, mach-es7000 and xen may need to co-exist
in the same kernel.

So, mach-xen may be a poor choice.  A subtle distinction
perhaps but when dealing with Linux kernel developers,
purity of thinking may avoid future patch submission
arguments.

So I'd vote for:

xen arch code in                arch/$(ARCH)/xen/
xen generic code in             drivers/xen/core/
xen arch includes in            include/asm-$(ARCH)/xen/
xen generic includes in         include/asm-xen/

though I realize this is not a democracy :-)

> -----Original Message-----
> From: Vincent Hanquez [mailto:vincent.hanquez@xxxxxxxxxxxx] 
> Sent: Wednesday, May 18, 2005 4:15 AM
> To: Chris Wright
> Cc: Magenheimer, Dan (HP Labs Fort Collins); 
> xen-devel@xxxxxxxxxxxxxxxxxxx; Mark Williamson
> Subject: Re: [Xen-devel] linux/arch/xen/i386 or linux/arch/i386/xen
> 
> On Tue, May 17, 2005 at 11:14:35AM -0700, Chris Wright wrote:
> > [snip]
> 
> So let's recap:
> 
> xen arch code in              arch/$(ARCH)/mach-xen/
> xen generic code in           drivers/xen/core/
> xen arch includes in          include/asm-$(ARCH)/mach-xen/
> xen generic includes in               include/asm-xen/
> 
> Now for arch that don't use mach-XX syntax we can probably make a
> xen directory instead of a mach-xen directory, but I'ld rather go with
> something consistant.
> 
> As well we can probably host a public tree in cambridge for anybody
> interested in the files reorganisation.
> 
> Any others thought, comments ?
> 
> -- 
> Vincent Hanquez
> 

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