linux-kernel - Re: [PATCH] x86_64: set cfg_size for AMD Family 10h in case MMCONFIG is used

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Date:	Thu, 13 Sep 2007 13:14:44 -0700
From:	Yinghai Lu <Yinghai.Lu@....COM>
To:	Andreas Herrmann <andreas.herrmann3@....com>
Cc:	Andi Kleen <ak@...e.de>, Greg KH <greg@...ah.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jeff Garzik <jeff@...zik.org>, Martin Mares <mj@....cz>,
	dean gaudet <dean@...tic.org>,
	Robert Richter <robert.richter@....com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86_64: set cfg_size for AMD Family 10h in case MMCONFIG
 is used

Andreas Herrmann wrote:
> On Thu, Sep 13, 2007 at 01:53:15PM +0200, Andi Kleen wrote:
>> On Thursday 13 September 2007 12:47, Greg KH wrote:
>>> On Thu, Sep 13, 2007 at 11:47:42AM +0200, Andi Kleen wrote:
>>>> On Thursday 13 September 2007 04:21, Yinghai Lu wrote:
>>>>> [PATCH] x86_64: set cfg_size for AMD Family 10h in case MMCONFIG is
>>>>> used.
>>>>>
>>>>> reuse pci_cfg_space_size but skip check pci express and pci-x CAP ID.
>>>> I just rejected a similar patch -- this should be done using MMCONFIG
>>> But what about for broken machines without the proper MMCONFIG entries?
>>> They still need a way to get access to this config space,
>> If there are any devices that need it. IBS and PCI-E error handling 
>> do, but they're quite obscure.
>>
>> Also so far we don't know of any Fam 10h systems without MMCONFIG
>> entries. Fam10h requires a new BIOS so it's reasonable to assume
>> that the new BIOSes will do better.
> 
> IMHO support for all config space access methods should be added to the kernel.
> And it should be added at a central point. Not waiting for drivers to do it
> their own way if they need to use it.
> 
> The more complicated/important question is how to decide which access method
> should be used for a device. (Something similar to the pci_mmcfg_fallback_slots
> stuff that exists already for K8 NB.)
> But that needs some more thinking.
> 
> Here a summary wrt family 10h extended config space access methods.
> (Most of this stuff I verified with some patched kernels. I didn't
> eavesdropping on the physical links though ...)
> 
> For family 10h we have 3 methods
> (1) "legacy" MMCONFIG access (via south bridge)
> (2) mmconfig access via CPU/NB (new with fam10h, using the new MMIO
>     config base MSR)
> (3) CF8/CFC ECS access (new with fam10h, has to be enabled in the NB_CFG MSR)

ECS access in NB_CFG_MSR is always enabled. because BIOS need to use that to do mem initialization.

mmconfig enablement in BIOS is depending ....

YH
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