Re: [Bug 10732] REGRESSION: 2.6.26-rc2-git4: X server failed startonX61s laptop

[Jeremy Fitzhardinge]

Hugh Dickins wrote:
> > And can we agree to never EVER use that PAGE_MASK thing (which was only 
> > ever meant to work on *addresses*) for any pte operations (including the 
> > definition of PTE_MASK)? Because PAGE_MASK is very much the word-size, and 
> > in 32-bit PAE, the page table entry is bigger.
> >
> > IOE, PTE_MASK should be a "pteval_t". And it should have absolutely 
> > *nothing* to do with PAGE_MASK. EVER.
> >     
>
> Yes, Jeremy makes it a pteval_t.  (My builds and Ingo's builds succeed,
> but I've not worked out how that goes down in assembly: there was an
> _AT macro in there before, which you've kept too - Jeremy?)
>   

I got rid of a bunch of _AT() uses because the constants aren't used in 
.S files anywhere.  Also, I couldn't see how to represent a 64-bit 
constant in assembler, so I wasn't sure of their correctness (the as 
manual is irritatingly vague on the matter).

> Yes, I'm highly resistant to taking untested patches here.  The two-liner
> I sent last night was about my fifth attempt to get it working, and I did
> start off from a small PTE_MASK correction which didn't work at all.  It
> looked rather like yours, I guess I missed the  __PHYSICAL_LOW_BITS part.
> Jeremy's goes a lot further, he'll know the gotchas better.
>   

__PHYSICAL_LOW_BITS is a bit more elegant than what I did there (the 
problem is getting a physaddr_t-width PAGE_MASK).  But the formulation 
in my patch certainly works.

   J
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