Merging 64 bit changes to -HEAD - part 2

[Alan Cox]

On 6/17/2010 5:30 PM, Randall Stewart wrote:
>
> On Jun 17, 2010, at 1:05 PM, M. Warner Losh wrote:
>
>>
>>
>> It was also a name-space collision, so we were using PG_x instead of
>> PG_y in the PTE code due to the overlap.  Maybe it all works now, but
>> that was the motivation for the change.
>
>
>
> Yes, basically if I remember right someone used
>
> PG_GLOBAL instead of PG_G. This caused the wrong bits
> to be set.
>
> In general I think its a BAD idea to have two name spaces in the
> same section of the system (VM) that have similar define's that mean
> different things.
>
>
> Far better to KEEP the PTE_xxx or for that matter pick something 
> else.. Just
> NOT PG_xxx

There is precedent for the PTE_ prefix: ia64 and powerpc.  I would stick 
with it.

(For the historically inclined, the name space collision goes back to 
CVS revision 1.1 of the relevant files, i.e., 1993.)

Alan