Re: [rfc] hw resource debugging checks

["Yinghai Lu" <yhlu.kernel@gmail.com>]

On Sun, Apr 13, 2008 at 8:52 PM, Arjan van de Ven <arjan@infradead.org> wrote:
>
> On Sun, 13 Apr 2008 12:29:30 -0700
>  "Yinghai Lu" <yhlu.kernel@gmail.com> wrote:
>
>  > On Sun, Apr 13, 2008 at 11:29 AM, Andi Kleen <andi@firstfloor.org>
>  > wrote:
>  > > > even I could talk to BIOS
>  > >  > engineers everyday and tell them how to fix the problem in
>  > >  > BIOS,  some still can not be fixed because of the legacy BIOS
>  > >  > framework or big mess.
>  > >
>  > >  ... so you opt to create the big mess in the kernel. Great.
>  > >
>  > >  And it does not even fixes a real problem, but getting
>  > >  mmconfig or the numa bus discovery to work is not really a too
>  > > serious issue anyways. At best it is the icing on the cake to enable
>  > >  some relatively obscure functionality and be a little more
>  > >  efficient, but nothing really fundamental.
>  > >
>  > >  But for those things just expecting a working modern BIOS is quite
>  > >  reasonable.
>  >
>  > it does fix real problem. when big system with several HT links, and
>  > every link some pcie slots.
>  > you fully load pci-e cards (with pci bridge). BIOS will stop assign
>  > io/mmio resource to left device if it run out of io port range.
>  > (though it is supposed to go on to allocate mmio to left devices) (
>  > modern pcie device only need mmio with drivers)
>  >
>  > With pre set range allocation in NB pci conf, kernel could allocate
>  > the resource in every peer root bus ranges.
>  > (the code for assign resource to device that is not assigned resource
>  > by BIOS --- already in kernel)
>  >
>
>  there is a really big difference between assigning PCI device resources
>  and doing a whole thing like MMCFG from scratch.
>
that MCONF patchset for AMD fam10h include
1. get mmconfig from MSR, MCFG is using that too, if that is right,
and we will get MCONF support when acpi support is off, and MCFG is
broken.
2. or assign 0xfc00000000 to that MSR, that is safe too.

YH