6ccf265bb0
avoid problems with some Pentium 4 cpus and some older PPro/Pentium2 cpus. There are several problems, some documented in Intel errata. This patch: 1) moves the kernel to the second page in the PSE case. There is an errata that says that you Must Not point a 4MB page at physical address zero on older cpus. We avoided bugs here due to sheer luck. 2) sets up PSE page tables right from the start in locore, rather than trying to switch from 4K to 4M (or 2M) pages part way through the boot sequence at the same time that we're messing with PG_G. For some reason, the pmap work over the last 18 months seems to tickle the problems, and the PAE infrastructure changes disturb the cpu bugs even more. A couple of people have reported a problem with APM bios calls during boot. I'll work with people to get this resolved. Obtained from: bmilekic
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