linux-kernel - Re: resource piix4_smbus conflicts with ACPI region SMRG

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Date:	Mon, 31 May 2010 21:13:51 -0600
From:	Robert Hancock <hancockrwd@...il.com>
To:	Richard Tillmore <rtillmore@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: resource piix4_smbus conflicts with ACPI region SMRG

On Mon, May 31, 2010 at 8:36 PM, Richard Tillmore <rtillmore@...il.com> wrote:
> On Mon, May 31, 2010 at 6:42 PM, Robert Hancock wrote:
>> On 05/31/2010 04:12 PM, Richard wrote:
>>>
>>> I upgraded to 2.6.34-rc6 and noticed a few new messages in dmesg.  I
>>> then installed 2.6.34 and the messages remain.
>>>
>>> PCI: Ignoring host bridge windows from ACPI; if necessary, use
>>> "pci=use_crs" and report a bug
>>> ACPI: PCI Root Bridge [PCI0] (0000:00)
>>
>> This is just an informational message.
>>
>>>
>>> ACPI: resource piix4_smbus [io  0x0440-0x0447] conflicts with ACPI
>>> region SMRG [??? 0x00000440-0x0000044f flags 0x47]
>>> ACPI: If an ACPI driver is available for this device, you should use
>>> it instead of the native driver
>>>
>>> The system is a Tyan Tiger S1832 motherboard with a P3 850Mhz
>>> processor running the latest bios.  Everything appears to work
>>> properly so I am unsure what the messages mean beyond the obvious.  I
>>> did a little research and was wondering if this is related to the no
>>> bootmem patches.  I have:
>>
>> Unless you need to use anything on SMBus (hardware sensors, essentially) you
>> don't have to worry about that one. It means that the kernel has detected
>> that the BIOS may potentially access the SMBus controller which may conflict
>> with usage of the controller from within the OS.
>
> I do use the lm78 sensor driver:
> lm78: Found an LM79 chip at 0x290
> and the Xsensors seem to work, the voltages and fan speeds change.
>
> But you are correct the lm75 driver isn't loading so I am not getting
> my cpu temperature.
>
> In 2.6.30.9 I have:
> Driver `lm78'
>  Detects correctly:
>  * Bus `SMBus PIIX4 adapter at 0440'
>    Busdriver `i2c-piix4', I2C address 0x2d
>    ISA bus, address 0x290
>    Chip `National Semiconductor LM79' (confidence: 6)
>
> Driver `lm75'
>  Detects correctly:
>  * Bus `SMBus PIIX4 adapter at 0440'
>    Busdriver `i2c-piix4', I2C address 0x4c
>    Chip `National Semiconductor LM75' (confidence: 6)
>  * Bus `SMBus PIIX4 adapter at 0440'
>    Busdriver `i2c-piix4', I2C address 0x4d
>    Chip `National Semiconductor LM75' (confidence: 6)
>
> In 2.6.34 I get:
> Driver `lm78'
>  Detects correctly:
>  * ISA bus, address 0x290
>    Chip `National Semiconductor LM79' (confidence: 6)
>
> So this is a regression.

You should be able to use acpi_enforce_resources=lax on the kernel
command line to allow the driver to load. The problem is that the
kernel can't tell if it's safe to allow a driver to access that
hardware since it may conflict with BIOS access (in some cases this
can cause serious problems like system overheating or spurious thermal
shutdowns if the BIOS also accesses the device to perform thermal
management) and so the default is to not allow it.
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