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If you get the 82093AA datasheet from Intel's website, it will contain the defacto standard for the way an I/O APIC is programmed. -----Original Message----- From: Hale Landis [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 17, 2004 11:29 AM To: [EMAIL PROTECTED] Subject: Re: [t13] apic mode fun why This message is from the T13 list server. On 17 Feb 2004 12:00:31 -0700, Pat LaVarre wrote: >This message is from the T13 list server. First let me answer Pat's #5 question first... >Q5) Is "APIC mode" documented in public? I have been searching for 2+ years for documentation on APIC, anything from a good overview to the technical details to what BIOS support exists, etc. Either this documentation does not exist or it is "secret". As for Pat's questions #1 through #3, APIC is nothing but a new style of interrupt controller. It has nothing to do with talking to a controller (ATA or otherwise) and nothing to do with sending commands to an I/O device. It is only a new way to handle interrupt routing and presentation of interrupts to the system's processor(s). >Q4) Can I reach "APIC mode" from 16-bit DOS code? And/or from a Gnu C >.exe? Sure, if you could find the documentation! My knowledge of APIC is limited but here is what I know... Traditional and APIC interrupt controllers can exist on the same motherboard. Normally one or the other is enabled (in BIOS setup). Switching from one to the other may require you to reinstall your OS (now that is really stupid!). I have seen some comments that it may be possible for both to be enabled at the same time (sounds like a mess to me). Traditional interrupt controllers support only 16 IRQs (actually less). APIC can support may more IRQs. We all know how the first 16 IRQs are routed to the x86 INT vectors (IRQ 0-7 to INT 8H-FH, IRQ 8-15 to INT 70H-77H). How the APIC IRQs 16 and higher are routed is unknown to me. APIC has a new/different method to "acknowledge" an interrupt (a different way to send EOI). How this EOI is done is unknown to me. I have a contact at a major chip company that claims he knows everything there is to know about APIC and I hope to talk to him this week. But if anyone can point us (Pat, me, everyone) to any good doc on APIC and the BIOS support for APIC that would be really great! Hale *** Hale Landis *** www.ata-atapi.com ***
