[Differential] D2535: New, experimental PMAP implementation for MIPS64

[sson (Stacey Son)]

sson added a comment.


  In https://reviews.freebsd.org/D2535#163954, @adrian wrote:
  
  > I committed the pagemask enumeration/printing logic to -head a while ago. We should gather some dmesg's from various embedded MIPS boards.
  >
  > IIRC, some of the mips24kc parts were only doing 4k pages.. :(
  
  
  This superpage/new pmap implementation really only applies to mips64.  To support superpages on mips32 the page table may need to be changed a bit.  Currently there isn't enough room in the PTE for the additional bits needed. e.g, bit for reference bit emulation (reference/valid bit), superpage flag, etc.
  
  FYI, I do have a patch kicking around for large kernel stack support that uses multiple wired TLB entries that might be useful for mips32 with only 4k page support.  Of course, I don't know if blowing the kernel stack (e.g. using NFS) is a problem for mips32 or not.  Brooks had it committed to CheriBSD at one time so I know it is in that repository.

REPOSITORY
  rS FreeBSD src repository

REVISION DETAIL
  https://reviews.freebsd.org/D2535

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To: sbruno, sson
Cc: adrian, brooks, jmallett, markj, alc, sbruno, rwatson, emaste, imp, freebsd-mips-list, dnelson_1901_yahoo.com, mizhka_gmail.com