[coreboot] PIC, APIC, XAPIC and XIOAPIC

ron minnich rminnich at gmail.com
Tue Mar 4 16:00:43 CET 2008

On Tue, Mar 4, 2008 at 2:08 AM, Feng, Libo <Libo.Feng at amd.com> wrote:

> In LB stage, only PIC mode is applied, isn't it? However, I remember some
> people of LB community told me there was no ISR except the debug ISR during
> LB. So does this mean it totally unnecessary to setup PIC via C00h/C001h IO
> port in LB?

PIC is set up in many mainboards so it is ready for the kernel. This
is because so many $PIR tables are wrong.

PIC is not needed for ISR, but coreboot only does ISR for the case of
running PCI (or VGA) ROMs anyway.

> APIC is setup only after OS runs and gets the interrupt routing from MPTable
> or ACPI table, is it correct? Then, what difference between APIC and XAPIC?
> Some documents say APIC has MMIO space registers at FEC00000h while XAPIC
> has PCI configuration space registers. But some documents seems to refer the
> same controller by APIC and XAPIC.

APIC is set up by kernel.


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