x86 MM titbits

Neil Conway (nconway.list@ukaea.org.uk)
Tue, 7 Jul 1998 22:35:46 +0000


I've just been browsing some Intel manuals...

Firstly, on the page-size issues that've been so prominent of late,
the guides say that the page-size extensions (4kB/4MB pages) allow
both page sizes to be available simultaneously (dunno about 2MB),
and in fact Intel recommend this as a way to free TLB entries by
using a 4MB page for the whole kernel...
Relevant to us maybe ?

Also, an interesting bit at the back of the PII developer's manual
says basically: "if you want to write kernels, there's some stuff you
might like to know that we won't tell you without an NDA" (full text
is included below).

Are the undocumented features liable to be of interest or use to us ?
Bit pointless really unless we can persuade Intel to cough up the info.
But then again, they do seem to have a reasonable attitude to Linux
these days, no ?

Neil
neil.conway@ukaea.org.uk

PS: here's the relevant bit from the manual:

14.1. ADDITIONAL INFORMATION
Some non-essential information regarding the Pentium II processor is
considered Intel
confidential and proprietary and is not documented in this publication.
This information is
available with the appropriate non-disclosure agreements in place.
Please contact Intel
Corporation for details.
This information is specifically targeted at software developers who
develop the following
types of low-level software:
operating system kernels
virtual memory managers
BIOS and processor test software
performance monitoring tools

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