Re: resource piix4_smbus conflicts with ACPI region SMRG

[Richard Tillmore]

On Mon, May 31, 2010 at 10:13 PM, Robert Hancock wrote:
> On Mon, May 31, 2010 at 8:36 PM, Richard 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.
<snip>
>>>> 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.

I booted with acpi_enforce_resources=lax and I now can get my CPU
temperature.  So is my having to add acpi_enforce_resources=lax an
effect of ACPI changes or bootmem changes?

Thanks,
Rich
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