Re: [RFC] Runtime allocation of PCI resources

From: Yinghai Lu
Date: Mon Jun 11 2007 - 14:11:19 EST

On 11 Jun 2007 20:11:24 +0200, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
Matthew Garrett <mjg59@xxxxxxxxxxxxx> writes:

> BIOS authors don't always program all the features of hardware. This is
> often the case for Intel IDE controllers, which are usually able to run
> in AHCI mode but are rarely configured to do so. Reprogramming them is
> easy enough other than the requirement for some MMIO space. If the BIOS
> hasn't allocated this, it's necessary for us to do so manually.

Traditionally we've had bad experiences forcing hardware to do something
the BIOS didn't consider. e.g. occasionally the BIOS has good reasons
to not allow it; maybe it knows about some errata or other problem
the kernel doesn't.

If you do this then don't make it default at least, but only allow
to force it use an option.

Esp for AMD system with several Hypertranport chain. try to allocate
pci resource in kernel also need some region adjust in NB
configuration space.

So leave some work to ACPI DSDT AML code at least

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