arm/158950: arm/sheevaplug fails fsx when mmap operations are enabled

[Kristof Provost]

On 2012-04-25 08:34:34 (-0600), Ian Lepore <freebsd at damnhippie.dyndns.org> wrote:
> Whenever I run into IO corruption that comes in 32-byte chunks I
> immediately suspect trouble in the busdma cacheline flush code.  A
> useful first step in narrowing that down is to change the data cache
> from write-back to write-through mode and see if the symptoms change.  I
> think for a sheeva cpu you'd do that in pmap_pte_init_arm10() in
> sys/arm/arm/pmap.c.  Change the xxx_cache_mode vars to be the same as
> they are in the pmap_pte_init_arm9() function just above it.
> 
I've had to disable it in pmap_pte_init_generic() rather than
pmap_pte_init_arm10(), but that does seem to prevent the corruption.

Regards,
Kristof