Re: [patch] Ignore MCFG if the mmconfig area isn't reserved in thee820 table.

From: Petr Vandrovec
Date: Thu May 18 2006 - 14:05:41 EST

Arjan van de Ven wrote:
Konrad Rzeszutek wrote:

That is definitely a problem - and the "sanity-check" can definitly bail
out on those BIOSes and not crash Linux. The other side of the coin is that BIOSes that do implement the MCFG/E820 correctly are penalized:

I hereby contest that it's implemented correctly if it's not marked reserved...

PCI Firmware Specification 3.0 (, page 42, notes for table 4-2, paragraph 2 says that firmware must report MCFG as reserved region. Last sentence of same paragraph says that resources may be optionally marked reserved by E820 or EFIGetMemoryMap, but must be always reported as motherboard resources through ACPI (for exact citation please see document itself, it is not freely available so I'm not going to copy-paste text from it without written permission from pcisig...).

So it seems to me that BIOS not reporting MMCONFIG as reserved through E820 is compliant, and what matters is that MMCONFIG must be reported as ACPI motherboard resource.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at