Feb 18, 2011 09:56:42 AM, [email protected] wrote:
Here is additional info from the lm-sensors FAQ as to why "acpi_enforce_resources=lax" is not recommended as a permanent fix:
http://www.lm-sensors.org/wiki/FAQ/Chapter3#Mysensorshavestoppedworkinginkernel2.6.31
My sensors have stopped working in kernel 2.6.31 ΒΆ
in the mainline 2.6.31 kernel, there is a change which causes hardware monitoring to no longer work on some motherboards. If this is happening for your motherboard, then when the lm_sensors service is starting you are probably getting an error like this:
FATAL: Error inserting it87
(/lib/modules/2.6.29-15.fc11.x86_64/kernel/drivers/hwmon/it87.ko): Device or
resource busy
And if you look at the kernel messages (using the dmesg command in a terminal for example) you will probably see something like this:
ACPI: I/O resource it87 [0x295-0x296] conflicts with ACPI region IP__
[0x295-0x296]
ACPI: Device needs an ACPI driver
With previous kernels hwmon drivers used to drive IO ranges which were potentially used by the ACPI code in your BIOS (which is active not only during but also after boot), we now explicitly check for this and if the ACPI code claims the IO-ports used by the hwmon chip, we no longer allow the hwmon driver to load.
Banging IO-ports of a chip from 2 different drivers, the Linux hwmon driver and the ACPI code is a really bad idea and can cause all sort of issues (including things like changing CPU / RAM voltage or clock speed). So the old behaviour was a really bad idea.
So even though this change in behaviour makes some people unhappy as to old behaviour happened to work without problems in their case (by sheer luck really), this change is really for the best!
If you have an Asus motherboard, chances are good there is an ACPI interface to read your sensors, which is safe, and no more sensors.conf tweaking needed for conversion formulas! Make sure you have the asus_atk0110 driver enabled in your kernel configuration to use this. You will also need lm-sensors version 3.1.0 or later.
If you want to restore the old behaviour (which might be dangerous) add: "acpi_enforce_resources=lax" to the kernel cmdline when booting (or add it in grub.conf to make this permanent).
Notes:
1) This change actually first appeared in the mainline 2.6.30 kernel, but due to a bug in 2.6.30, it didn't take effect until 2.6.31, see: http://bugzilla.kernel.org/show_bug.cgi?id=13967
2) Some distributions have made this change earlier (e.g. Fedora has this change since kernel 2.6.29)
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