linux-kernel - Re: [PATCH] x86/PCI: never allocate PCI MMIO resources below BIOS

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Date:	Mon, 26 Apr 2010 18:41:55 -0700
From:	Yinghai <yinghai.lu@...cle.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	Andy Isaacson <adi@...apodia.org>,
	"R. Andrew Bailey" <bailey@...mai.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, guenter.roeck@...csson.com,
	"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>, yaneti@...lera.com
Subject: Re: [PATCH] x86/PCI: never allocate PCI MMIO resources below    BIOS_END

On 04/26/2010 06:27 PM, Linus Torvalds wrote:
> 
> 
> On Mon, 26 Apr 2010, Jesse Barnes wrote:
>>
>> Glad we agree.  As I said (and echoing Bjorn), I think it would be best
>> to reserve this space in a way that doesn't just use IORESOURCE_BUSY.
>> We want and need to do allocations from the special region, so we
>> should mark it as such.
> 
> I think Bjorn's patch to pcibios_align_resource() is really good and 
> clever, and I think it should take care of the need for IORESOURCE_BUSY, 
> no? We do want to let devices that are _already_ allocated there insert 
> their resources, it's just that we never want to allocate new ones in the 
> low 1M region.

case A:
bus 0: --- bus X --- device Y
if the BIOS only assign range to to BUS X bridge with 0xB0000, and
device Y is not assigned.  then with Bojorn's patch, device Y can not
get right resource allocated on first try.


> 
> Do we actually have a regression left with Bjorn's patch?

also find one AMD system:

[    6.960006] PCI: Using host bridge windows from ACPI; if necessary, use "pci=nocrs" and report a bug
[    6.984225] ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-06])
[    7.023528] pci_root PNP0A03:00: host bridge window [io  0x0000-0x03af]
[    7.024014] pci_root PNP0A03:00: host bridge window [io  0x03b0-0x03bb]
[    7.028005] pci_root PNP0A03:00: host bridge window [io  0x03bc-0x03bf]
[    7.032005] pci_root PNP0A03:00: host bridge window [io  0x03c0-0x03df]
[    7.036005] pci_root PNP0A03:00: host bridge window [io  0x03e0-0xefff]
[    7.040011] pci_root PNP0A03:00: host bridge window [mem 0xd8000000-0xe7ffffff]
[    7.044005] pci_root PNP0A03:00: host bridge window [mem 0xf0000000-0xfe9fffff]
[    7.048005] pci_root PNP0A03:00: host bridge window [mem 0xfec00000-0xfed0ffff]
[    7.052005] pci_root PNP0A03:00: host bridge window [mem 0x000a0000-0x000bffff]
[    7.056011] pci_root PNP0A03:00: host bridge window [mem 0xfed20000-0xffffffff]

[    0.000000]  BIOS-e820: 0000000000000100 - 0000000000098c00 (usable)
[    0.000000]  BIOS-e820: 0000000000098c00 - 00000000000a0000 (reserved)
[    0.000000]  BIOS-e820: 00000000000e6000 - 0000000000100000 (reserved)
[    0.000000]  BIOS-e820: 0000000000100000 - 00000000d7fa0000 (usable)
[    0.000000]  BIOS-e820: 00000000d7fae000 - 00000000d7fb0000 (reserved)
[    0.000000]  BIOS-e820: 00000000d7fb0000 - 00000000d7fbe000 (ACPI data)
[    0.000000]  BIOS-e820: 00000000d7fbe000 - 00000000d7ff0000 (ACPI NVS)
[    0.000000]  BIOS-e820: 00000000d7ff0000 - 00000000f0000000 (reserved)
[    0.000000]  BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
[    0.000000]  BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
[    0.000000]  BIOS-e820: 00000000ff700000 - 0000000100000000 (reserved)
[    0.000000]  BIOS-e820: 0000000100000000 - 0000008028000000 (usable)

pci assign unassign code could use range like [mem 0xfed20000-0xffffffff] wrongly.

YH
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