On Thu, Aug 28, 2008 at 1:05 PM, Linus Torvalds

 wrote:

quoted text
>

>

> On Thu, 28 Aug 2008, Yinghai Lu wrote:

>>

>> so could let BAR res register at first, or even pnp?

>

> Well, I'm not sure whether PnP or e820 should be first, as long as any

> "real hardware" probing takes precedence over either. I _suspect_ that

> e820 is more trustworthy, which implies that PnP should probably be added

> last. It would be good to have some idea what Windows does, since usually

> all the firmware bugs are essentially hidden by whatever that other OS

> happens to do.

>

> The basic rule really should be: "What do we trust most?" and probe things

> in that order.

>

> So e820 is fairly trustworthy, but we know that it will have various

> random things marked as reserved because they are special in some way (but

> we don't know _how_ they are special - they may well be real BAR's that

> just have a fixed meaning to ACPI or whatever).

>

> But we obviously trust _part_ of it (the RAM stuff) more than we trust

> other parts. So it does make sense to consider that separately.

>

> PnP I personally wouldn't trust at all, except as a way to keep dynamic

> resources away from those things, which is why I'd put it last. But that's

> just my personal gut feeling.

>

> Hardware we generally trust more than any firmware, but even hardware can

> have bugs. And some classes of hardware tends to be less buggy than others

> (ie I'd trust some on-die APIC base pointer before I would trust a Cardbus

> controller BAR, for example).

ok, will move e820_reserve_resource_late to pcibios_resource_survey(),

so it is called vi pci_subsys_init before pnp_system_init
YH

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