Booting 2.6.26-rc1 on an old Coppermine PIII, I'm greeted with:
I know about Intel's PAT erratum (only 4 PAT entries work) and
understand that the kernel might not want to use a half-broken
PAT implementation, but the statement above is blatantly false:
the kernel IS built with PAT support and the CPU DOES have
(half-broken) PAT HW support as /proc/cpuinfo from earlier kernels
confirms.
arch/x86/kernel/cpu/common.c unconditionally disables PAT and
then reenables it for certain vendor/family/model combinations.(*)
Then mm/pat.c comes along, finds !cpu_has_pat, and prints the
bogus message above.
IMO, it would be a lot nicer if common.c printed a warning when
it disables PAT due to the erratum, then the printk() in pat.c
could be something like "PAT support absent or disabled".
(*) common.c enables PAT for all Intel family 15 CPUs. Is that
correct? I don't have the spec updates in front of me, but I
seem to recall the PAT erratum existed also in early P4s.
/Mikael
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