Re: [patch] Ignore MCFG if the mmconfig area isn't reserved in the e820 table

[Andi Kleen <ak@suse.de>]

Arjan van de Ven <arjan@linux.intel.com> writes:

> On Thu, 2006-03-23 at 20:02 +0100, Arjan van de Ven wrote:
> > > That is e820_mapped(address, address+size, E820_RESERVED)
> > > 
> > > And not having a size is definitely wrong on i386 too.
> > 
> > s/wrong/not selective enough/
> > 
> > and e820_mapped doesn't check this either anyway, at least not the way
> > you imply it does.
> > 
> > I'll do a new patch using this for x86_64 though, no need to make a
> > second function like this.
> 
> 
> There have been several machines that don't have a working MMCONFIG,
> often because of a buggy MCFG table in the ACPI bios. This patch adds a
> simple sanity check that detects a whole bunch of these cases, and when
> it detects it, linux now boots rather than crash-and-burns. The accuracy
> of this detection can in principle be improved if there was a "is this
> entire range in e820 with THIS attribute", but no such function exist
> and the complexity needed for this is not really worth it; this simple
> check already catches most cases anyway.

I added the patch to my patchkit now. I also have an older patch (needs a bit
more cleanup) that checks for all busses if they are reachable using MCFG
Still needs some more work and interaction check with PCI hotplug though.


-Andi