Calum Mackay wrote:
> The radeon kernel driver source includes (via drm_memory.h) 
> linux/vmalloc.h, iff VMAP_4_ARGS is defined. The latter includes (on 
> i386) asm/asm-i386/pgtable.h, which includes asm/asm-i386/processor.h.
> 
> processor.h defines some inline functions [set_in_cr4() & 
> clear_in_cr4()] which reference mmu_cr4_features.

Sadly, this isn't the full story, since the radeon code doesn't 
reference *_in_cr4.

The radeon code calls io/agp remap functions - again only ifdef 
VMAP_4_ARGS - which do however call __flush_tlb_all(). This manipulates 
the PGE bit via mmu_cr4_features.

apols for the spam...

cheers,
Calum.