linux-kernel - Re: [PATCH -v2 1/2] x86: Reserve [0xa0000, 0x100000] in e820 map

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Message-ID: <4BC4F703.5030700@oracle.com>
Date:	Tue, 13 Apr 2010 15:58:11 -0700
From:	Yinghai <yinghai.lu@...cle.com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Bjorn Helgaas <bjorn.helgaas@...com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Andy Isaacson <adi@...apodia.org>, guenter.roeck@...csson.com,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Renninger <trenn@...e.de>
Subject: Re: [PATCH -v2 1/2] x86: Reserve [0xa0000, 0x100000] in e820 map

On 04/13/2010 03:41 PM, H. Peter Anvin wrote:
> On 04/13/2010 03:29 PM, Yinghai wrote:
>>>
>>> We have talked about a need to resolve this before.
>>
>> current code for mmio that is just below 4g, if some PCI BAR use that range, and those range is falling into E820_RESERVED,
>>
>> those range still can be claimed, but driver can not use pci_request_region() later.
>>
>> So We still
>> 1. rely that BIOS does not reserve the [0xa0000, 0xe0000)
>> 2. kernel only reserve the range when we make sure these is legacy device on that range.
>>
> 
> This really isn't sufficient.  There are systems in the field which
> marks a memory range reserved in E820 because it a device pointed there,
> and it doesn't want that device moved because it is used by an SMM handler.
> 
> This was reported quite a while ago (like two years.)  I can dig up the
> thread if it matters.

Are you sure? what is BAR range? greater than 1M ?

e820_reserve_resources() will make that range to be reserved and BUSY in resource tree.
and if driver for that device want to call pci_request_region, it will get failure...

YH
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