Grrr: Cache flushing...

David S. Miller (
Sun, 2 Jul 1995 01:10:42 -0400

Date: Sun, 2 Jul 1995 15:03:39 +1000 (EST)
From: Andrew Cagney <>

o cache lines (blocks) are 2^5 bytes
o there are 2^7 sets
o there are 2(603), 4(604,603+?), 8(601) blocks per set
o virtually indexed (from the above, PPC bits 20-26)
o physically taged

Working this through you find that a block (for all sets) covers exactly
one 4k page ( == PPC page size) and as a consequence, this means that
for the PowerPC, the above is a none issue (and very nice change at that

Nice, looks like they definately put some decent forethought into
this. Hopefully, my setup will allow different ports to optimize away
unnecessary operations. Doing the shared mappings correctly may be a
pain still (this is in general) due to the fact that the linux shared
mapping code has no concept of "is this a good place to map this
area?" in respect to aliasing and such. Mainly because this is a
non-issue on the ix86/alpha. If I'm not feeling so adventurous I'll
hold off on the shared stuff until somebody really needs it (I'll
probably be the first if and when I start playing around with shared

David S. Miller