Re: [Xen-devel] Compile pvops kernel xen/stable-2.6.32.x error

[Kevin.Buckley@xxxxxxxxxxxxx]

In reference to

 http://lists.xensource.com/archives/html/xen-devel/2010-10/msg01374.html

> arch/x86/xen/mmu.c:163: error: __pcpu_scope_xen_cr3 causes a section
type conflict
> arch/x86/xen/mmu.c:164: error: __pcpu_scope_xen_current_cr3 causes a
section type conflict
> arch/x86/xen/mmu.c:163: error: __pcpu_unique_xen_cr3 causes a section
type conflict
> arch/x86/xen/mmu.c:164: error: __pcpu_unique_xen_current_cr3 causes a
section type conflict

Firstly, I appreciate that the original thread started a couple of
months back but just to say that I recently have seen those messages
and discovered what was causing them in the environment I was compiling
in so, having found the thread, I thought I'd post my findings,
especially as the thread issue doesn't seem to have been concluded.

I first saw the messages when trying to build a kernel which I had
configured, starting from a

 make mrproper; make allmodconfig

on a kernel tree pulled as follows:

git checkout -b xen/stable-2.6.32.x origin/xen/stable-2.6.32.x

as described in:

http://bderzhavets.wordpress.com/2010/04/24/set-up-ubuntu-10-04-server-pv-domu-at-xen-4-0-dom0-pvops-2-6-32-10-kernel-dom0-on-top-of-ubuntu-10-04-server/

and using Ubuntu's GCC 4.4.3 (so a more "recent" one than the OP's 4.1)

I had not seen those messages before re-configuring the kernel and
had, indeed  built a working, in terms of Xen, kernel using that
checked-out source and the instructions above.

I then came to look at something else that didn't appear to work
properly for me and so thought I'd go back and modularise as much
as possible and so try and see what was being accessed hence the

 make allmodconfig

I did however set all the Xen-related config settings to match those
from the working .config file I already had.

I thus assumed that there's some mismatch between compilation in the
default config that one gets after doing the:

 make allmodconfig

and the "default" config to which one merely makes Xen-specific
changes when doing a

 make menuconfig

and went looking.



OK, that's the background, the info I want to pass on is this:

for me, the error messages are effectively toggled if one either
defines (see errors) or does not define (no errors) the kernel
config value:

CONFIG_DEBUG_FORCE_WEAK_PER_CPU

which is an option living in

 lib/Kconfig.debug

however the Kconfig help implies it is possibly related to s390 and
alpha architectures.

That seems to be the only change needed to, and indeed the only change
I have found so far which does, make the build fail in

 arch/x86/xen/mmu.o

in the way the OP describes.


In case there've been any explicit fixes, not posted into this thread,
in the meantime, I would have done the source pull around Nov 23rd.

Hoping this is useful, apologies if not,
Kevin

-- 
Kevin M. Buckley                                  Room:  CO327
School of Engineering and                         Phone: +64 4 463 5971
 Computer Science
Victoria University of Wellington
New Zealand


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel