linux-kernel - Re: APEI: Can not request iomem region for GARs

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Date:	Tue, 30 Aug 2011 08:57:14 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
CC:	Pavel Ivanov <paivanof@...il.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"Brown, Len" <len.brown@...el.com>
Subject: Re: APEI: Can not request iomem region for GARs

On 08/29/2011 10:48 PM, Bjorn Helgaas wrote:
> On Sun, Aug 28, 2011 at 7:27 PM, Huang Ying <ying.huang@...el.com> wrote:
>> On 08/26/2011 09:43 PM, Bjorn Helgaas wrote:
>>> On Thu, Aug 25, 2011 at 10:13 PM, Huang Ying <ying.huang@...el.com> wrote:
>>>> Hi, Pavel,
>>>>
>>>> Sorry,  there is a minor issue in the patch.  Do you have time to try
>>>> the updated version attached.
>>>
>>> I think Yinghai's patch is a better approach (though it needs a changelog).
>>>
>>> The ACPI NVS space should not be marked as "busy" by the e820 code in
>>> the iomem_resource tree.
>>>
>>> It's way too complicated to mess around with registering NVS space and
>>> trying to deal with it specially in APEI.
>>
>> ACPI NVS is different, it can be used only by firmware, and its
>> interpreter, such as ACPI AML interpreter and APEI interpreter.  It can
>> not be used by ordinary driver.  If my understanding is correct, this is
>> why ACPI NVS is marked as busy.
> 
> I don't understand why ACPI NVS is different.  If we reserve it in
> iomem_resource (without marking it busy), it's already unavailable to
> anything else unless you know something connected to the NVS region.

I think ACPI NVS can be seen as reserved by ACPI or firmware
interpreter.  So that, all other drivers should not access it.

Best Regards,
Huang Ying
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