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Re: CVS commit: src/sys/uvm

Matt Thomas modified UVM colour matching scheme;

Modified Files:
       src/sys/uvm: uvm_extern.h uvm_fault.c uvm_km.c uvm_page.c

Log Message:
Add better color matching selecting free pages.  KM pages will now allocated
so that VA and PA have the same color.  On a page fault, choose a physical
page that has the same color as the virtual address.

This change is a big forward-reap to have VIPT-safe NetBSD VM for R4000 and
modern ARM.  Combined with matched KVA selection against UVA, found in
vm_machdep.c::vmapbuf(), there remains little ocasion where VM chooses
mistakenly wrong colour combination to bind VPN and PFN.

The entire effect is to eliminate the necessity of VIPT fixup efforts in 
pmap.c and ends up with improving the cache effeciency in large degree.  This
is _the intent_behind VIPT design.  So far OS virtual memory strategy paid 
attention to make VIPT cache work correctly.

Toru Nishimura / ALKYL Technology

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