On Monday, January 12, 2009 12:45 am Crane Cai wrote:
> Hi Jesse,
>
> Sorry to disturb you. This is a question needs you help:
>
> In file: $(KERNEL_SRC)/arch/x86/kernel/early-quirks.c
> function early_quirks:
> ---
> void __init early_quirks(void)
> {
> int num, slot, func;
>
> if (!early_pci_allowed())
> return;
>
> /* Poor man's PCI discovery */
> => for (num = 0; num < 32; num++)
> for (slot = 0; slot < 32; slot++)
> for (func = 0; func < 8; func++) {
> /* Only probe function 0 on single fn
> devices */
> if (check_dev_quirk(num, slot, func))
> break;
> }
> }
> ---
>
> Why we only scan first 32 pci bus? We know in spec there are 256 pci
> bus.
Probably because we haven't had a need for it yet. The early quirks are
pretty limited in scope, affecting just a few chipsets. Doing a full scan
when we don't need one would be overkill.
And in fact, I have a patch in my queue from Andi that limits the scan to the
root bus, since scanning sub-busses was triggering some early quirks
incorrectly.
--
Jesse Barnes, Intel Open Source Technology Center
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