lkml.org 
[lkml]   [2010]   [May]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] x86, hweight: Fix UML boot crash
On 05/30/2010 10:03 AM, Borislav Petkov wrote:
> Obviously UML cannot stomach callee reg-saving trickery
> introduced with d61931d89be506372d01a90d1755f6d0a9fafe2d (x86:
> Add optimized popcnt variants) and oopses during boot:
> http://marc.info/?l=linux-kernel&m=127522065202435&w=2
>
> Go ahead and fall back to the software hweight* routines on UML.

I actually don't understand why UML can't stomach that... it would work
exactly the same in userspace as in kernel space. The only thing that I
can think of is if UML overrides the CFLAGS including the per-file
CFLAGS, but that would seem to cause all kinds of other issues.

I would also be a lot happier if this was handled in
<asm/arch_hweight.h> than in <asm/bitops.h>. Finally, if UML really
can't handle this, then ARCH_HWEIGHT_CFLAGS should be disabled on UML.

This bothers me, because it really feels like something is fundamentally
broken in UML tryingto track the upstream architecture, and this is just
a bandage.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.



\
 
 \ /
  Last update: 2010-05-30 20:43    [from the cache]
©2003-2011 Jasper Spaans