Fixing the R4000 end of page bug

>>>>> "Stephen" == Stephen M
Rumble <stephen.rumbleutoronto.ca> writes:

 Stephen> Hello all, I've begun looking into fixing some
long-standing
 Stephen> problems with revision 2.2 R4000 CPUs on SGI
systems and
 Stephen> would like any input whatsoever from those more
experienced
 Stephen> with MIPS. The most prominent bug in this
revision occurs
 Stephen> when a branch or jump exists as the last
instruction in a
 Stephen> page, the following page (containing the delay
slot
 Stephen> instruction) is not mapped, and a few other
conditions
 Stephen> (including a data cache miss) are met by the
two prior
 Stephen> instructions. ...

Sounds like the old SB1 rev 1 bug.  The best answer is to
use the same
solution they used, which is to tweak the GCC code generator
to align
all branches to modulo 8 boundaries.  That's simple,
reliable, and has
very little performance impact.

    paul