[coreboot] PIC, APIC, XAPIC and XIOAPIC

Feng, Libo Libo.Feng at amd.com
Wed Mar 5 09:25:11 CET 2008

Yes. I think that after power on, IOAPIC works on PIC mode or virtual wire mode by default. But no device use interrupts in both coreboot and FILO, keyboard, vga, serial port all polling. I check the mptable.c, some people set the IOAPIC in PIC mode via c00h/c01h, now that no device uses it, why they set it? Maybe at the very beginning of OS, PIC mode is applied before IOAPIC is enabled. My understanding is correct or not? Thank you.

Best Regards

??? Feng Libo @ AMD  Ext: 20906
Mobile Phone: 13683249071
Office Phone: 0086-010-62801406

-----Original Message-----
From: Rudolf Marek [mailto:r.marek at assembler.cz] 
Sent: Wednesday, March 05, 2008 4:11 PM
To: Feng, Libo
Cc: coreboot at coreboot.org
Subject: Re: [coreboot] PIC, APIC, XAPIC and XIOAPIC


You need to put at least SB IOAPICs in virtualwire mode. Thats what BIOS should do. CHeck the Multiprocessor Specs 1.4 for details. (or VIA 8237 code in



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