I am bizy on my own operating system. its all working fine and all, but i also want to be able to use the APIC so i can get into SMM-mode (system management mode).  (To get into SMM-mode i need to generate an SMI and there for i need the APIC)

I got some info on the local Apic from the basic intel proc. manuels. so i know how to turn the local APIC on. i just dont know how to use the I/O APIC (or Global Apic), which handels the external interupts (the IRQ's).

Does any one have some info on the Local/Global or I/O APIC.


Posted on 2005-11-01 14:24:44 by pyr0_mathic

Well i found a doc about the IO-Apic, (look at attachment).

The base addr is FEC0.xy00 according to the Doc. (x = 0 to F, y =0/4/8/C)
and then there is a reference to the "APIC Base Relocation Register", which should be located on the PIIX3.

But how can i get to the PIIX3? so how can i get the base of the IO-APIC's  memory mapped registers.

Any Comment is appriciated

Posted on 2005-11-03 16:58:48 by pyr0_mathic
Try to get the developers manual of your Chipset!
If your chipset is from Intel, it will be easy to find ...

Posted on 2005-11-03 21:32:48 by Opcode
hi, once more...

Whell, i got a Soltek main-board, and i have 2 soltek-pc's. on both the io-apic, isnt where it should have been, at FEC0.0000.

i also tested it on my intel-(P4C800) mainboard, on that one i was able to write to the io-apic.

But the problem is i cant find much about Soltek-main boards.

Posted on 2005-11-30 06:09:58 by pyr0_mathic
here http://mitglied.lycos.de/shiceisdasdoch/pci.rar are 2 pdfs that describe how to get the content of the "APIC Base Relocation Register" i tried the method described in 290476.pdf by accessing I/O address 22/23 but i think the data i got wasnt correct.i think i82371FB.pdf is a newer document and you should try this one to get the relocations.if you figure out how to do it pls tell me!
Posted on 2005-12-01 07:59:17 by sHice

thx, for the link. am reading it right now, (it seems to be promesing). and yes when i find out how to use the io-apic ill tell u how it can be done.

Posted on 2005-12-01 14:31:23 by pyr0_mathic