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Hi! I was looking through some linux kernel documentation when it suddenly hit
me that enabling MTRRs (Memory Type Range Registers) would be cool for the DOS
build of Allegro. On linux and windows this is taken care by the drivers, but
not on DOS. MTRRs are a feature present on Pentium Pro and up (including
newer AMDs, Cyrix and other clones). Enabling MTRRs can only be done on PCI and
AGP adapters but it will supposedly speed up datatransfer rate by a factor of
2.5 or greater due to burst-write/write-combining.
I know enough on PCI and AGP to code a routine which fetches io adresses and
memory sizes from the display adapter, however i fear supporting the different
CPUs will be a little tricky. AMD, Cyrix and Intel have all different
implementations of MTRR if i understood the linux kernel correctly.
I'll take a look on internet to see if i can find some docs on MTRRs so that i
can start to code something useful. Is this something you all think will be
worth having in allegro and also are there somebody with knowledge on this type
of programming which could lend a hand? my assembler skills might be a bit
rusty. ;o)
--
Sincerely Henrik Stokseth.
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"Linux is keyboard friendly. I don't smash it like I used to with Windows."
Email: hstokset@xxxxxxxxxx Homepage: http://hstokset.n3.net