Re: CVS commit: src/sys/arch/amd64/include

[David Holland <dholland-sourcechanges%netbsd.org@localhost>]

On Sun, Jan 15, 2012 at 04:48:31PM +0000, Cherry G. Mathew wrote:
 > Module Name: src
 > Committed By:        cherry
 > Date:                Sun Jan 15 16:48:31 UTC 2012
 > 
 > Modified Files:
 >      src/sys/arch/amd64/include: pmap.h
 > 
 > Log Message:
 > for xen on amd64 PDP_BASE points to the per-cpu ci->ci_kpm_pdir copy of 
 > *pmap_kernel()*'s L4 pdir, which is an alias for ci->ci_kpm_pdir. This is 
 > unlike PAE, where PDP_BASE points to the per-pmap pm_pdir consisting of 4 
 > pages, the last of which is the "shadow". This "shadow" is not used directly 
 > in an active pmap, since it duplicates the kernel space and, for PAE, xen 
 > dissallows multiple cpus pointing to the same L3[3] page. Therefore, we use 
 > a per-cpu copy of the pmap_kernel() pdir's L3[3] page, 
 > ci->ci_pae_l3_pdir[3], while L3[0-2] point to the original pmap's pm_pdir[0 
 > - 2]. Thus the "shadow" pdir only exists on i386 PAE. Note that on PAE, the 
 > recursive PDIR_SLOT_PTE is not per-cpu, and therefore cannot be made to 
 > point to per-cpu pdirs via (L4_BASE + PDIR_SLOT_PTE), unlike xen x86_64 
 > where this is exactly the case.

in the future please word-wrap your commit messages...

-- 
David A. Holland
dholland%netbsd.org@localhost