On Mon, 2009-09-07 at 17:56 +0200, Dirk Behme wrote:

Catalin Marinas wrote:

quoted

There is a glibc patch to allow fully position-independent code and
avoid CoW for text pages:

http://sourceware.org/ml/libc-ports/2008-10/msg00009.html

We tested it and it seems to solve the problem without requiring a
kernel patch.

Regarding "fix the tool chain/libc and not the kernel":

The initial issue we are discussing here was found with a user space 
application downloaded as binary. Namely Ubuntu-ARM. While we could 
try to fix some tool chains, we never will be able to fix all tool 
chains out there. There will be ever some binaries compiled with a 
non-patched tool chain, resulting in ARM11 MPCore failures.

Please don't get me wrong, I'm in favour of a kernel fix even though
future toolchains may avoid this problem. I'm just trying clarify the
issue and get another opinion from Russell or others on this list.

Additionally, this Ubuntu ARM port runs fine on single core ARM11 
(e.g. N800) or Cortex A8 (e.g OMAP3 based BeagleBoard). It's my 
understanding that the issue we are discussing here is ARM11 MPCore 
kernel (cache handling?) specific, then. 

It's a problem with write-allocate caches, it isn't related to SMP. When
CONFIG_SMP is enabled, the kernel sets the cache policy to writealloc.

-- 
Catalin