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SubjectRe: [rfc] hw resource debugging checks
On Sun, 13 Apr 2008 22:01:23 -0700
"Yinghai Lu" <yhlu.kernel@gmail.com> wrote:

> 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.

using MCONF when the ACPI support isn't there is just a deathtrap.
To be honest, if you want to break the AMD machines out there, who am
I to care about that, I work for Intel. But I'm worried someone thinks
this can be done for Intel based systems too, and then carry over all
the bad bugs to those as well ;(



--
If you want to reach me at my work email, use arjan@linux.intel.com
For development, discussion and tips for power savings,
visit http://www.lesswatts.org


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