PATCH: enable use of memory beyond kseg0

[M. Warner Losh]

In message: <dffe84831003191148g7915a5cn268c1324b18177b5 at mail.gmail.com>
            Neel Natu <neelnatu at gmail.com> writes:
: Hi JC,
: 
: On Fri, Mar 19, 2010 at 5:18 AM, C. Jayachandran
: <c.jayachandran at gmail.com> wrote:
: > On Tue, Mar 16, 2010 at 7:05 AM, Neel Natu <neelnatu at gmail.com> wrote:
: >> This patch enables use of physical memory that is beyond the direct
: >> mapped kseg0 region.
: >>
: >> The basic idea is to use KVA from the kseg2 region for mapping page
: >> table pages that lie beyond the direct mapped region.
: >>
: >> The TLB miss handler can now recursively fault into the TLB invalid
: >> handler if it dereferences a kseg2 page table page address that is not
: >> in the TLB. The TLB invalid handler had to be extensively modified but
: >> in the end came out much cleaner.
: >>
: >> I have tested this on a uni and multi-processor Sibyte with 1GB of
: >> memory. It would be useful if this patch had some independent testing
: >> as well.
: >>
: >> Please review.
: >>
: >> http://people.freebsd.org/~neel/mips_beyond_kseg.diff
: >
: > This fixes the crash I was seeing during 'make -j16 buildworld' on
: > XLR. The buildworld completed after running about 6 hours over NFS
: > mounted src and obj dir, so the patch looks good. I haven't done any
: > performance comparisons yet.
: >
: 
: Thanks a lot for taking the time and effort to test this - much appreciated.

I think you can go ahead and commit it.  My eyeball review makes me
think it will work.  I've not had a chance to try them out on my
Octeon board, but don't let my lack of time hold this up now that we
know it helps XLR.

Warner