cvs commit: src/sys/amd64/amd64 amd64_mem.c

[Peter Wemm]

peter       2003/11/21 17:11:07 PST

  FreeBSD src repository

  Modified files:
    sys/amd64/amd64      amd64_mem.c 
  Log:
  Argh!  The Athlon64 and Opteron only implement 40 bits of address space in
  the MTRR Base/Mask registers.  If you use the documented algorithm in the
  systems programming guide, you'll get a GPF. The only thing that has
  prevented this so far is that the bios pre-sets some MTRR entries which
  we mis-interpreted sufficiently to fool the memcontrol interface into
  thinking all the address space was taken and therefore rejected XFree86's
  requests.  However, not all bioses do this..  You get an insta-panic in
  that case.  Grrr.  A better fix (dynamic mask) will happen by 5.3/5-stable
  so that we automatically adapt to more than 40 physical bits.
  
  Approved by:  re (scottl)
  
  Revision  Changes    Path
  1.23      +4 -5      src/sys/amd64/amd64/amd64_mem.c