RE: [Xen-devel] PG_arch_1

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

> >In any case, PG_arch_1 is used for other purposes on ia64, ppc,
> >ppc64, sparc64, arm, mips, pa-risc, and even has semantics for
> >linux arch-neutral code (look for PG_Arch_1 in
> >linux/Documentation/cachetlb.txt... does Xen depend on this
> >behavior?), and the eventual goal is to merge upstream,
> >it might be best if Xen defines it as a new bit ("PG_foreign"?
> >no sense being vague by calling it PG_arch_2) rather than
> >overloads PG_arch_1?
> 
> I prefer to the "vague" name here. By using PG_foreign, how 
> can this bit be utilized by other places when running out of 
> virtualization world? Since these bits are *jealously* 
> guarded, name of the new bit should encourage more usages 
> instead of special purpose.

That's exactly the problem.  If any Linux arch sees the bit
as generic and decides to use it for some other purpose, then
Xenlinux can't use it anymore.

Dan

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