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SubjectMTRR testbeds??

In rummaging through the IDT WinChip Doc's, i discovered that they support
thier own variant of the PPro/PII MTRR's (their "Memory Configuration
Registers"), and can be set to write-combine for strings, stacks, and
non-strings/non-stacks (as well as weak/strong ordering and some other
stuff)...I've started writing some code in the hopes of merging it
eventually with the existing MTRR code...(i'm running 2.1.132)

Now the question: I've written a quick and dirty module that simply
modifies the registers...it APPEARS to work, but i can't tell on a CPU
point of view because the MCR's are write-only, and i can't read them
back to make sure they wrote right (is ther some other way? does 'wrmsr'
return a value i haven't found yet?) .. However, are there any tests i can
run on X to find out if it really is working? i tried x11perf with and
without the module loaded, but it appears to run about the same each run..
is there any other tests? will x11perf even show an improvement?

also, what is the best setting for the X linear framebuffer?
writecombining for stacks? strings? both? neither?
I have a matrox Mystique in my test machine, with 3 memory addresses
listed in /proc/pci, 0xe0000000 [0xe0000008], 0xe1000000, and 0xe08000000.
X perorts that Liner Framebuffer at 0xe0000000, and MMIO region and
0xe1000000...which region, or both, should be set up? (or, tell me to shut
up and ask the X people ;)

any help/comments appreciated...
john.c
- --
/* John Clemens http://www.rpi.edu/~clemej _/ Speak Softly, */
/* RPI CompE, 2000 clemej@rpi.edu _/ Drive a Sherman Tank */


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