SMM Function for BIOS thermal controls?

Question

Hi, I have been looking into the SMM functions in the dell BIOS which the i8k driver uses to modify the fan speeds and it seems when I attempt to change them the BIOS sets it right back. To get around this I need to do the Fn+15324, FN+r magic and disable the 'BIOS thermal control' which probably calls an SMM function and I want to incorperate this into the driver, as it needs to be done every reboot. However I don't know how to work out which function is actually being called or how to call it, does anyone have any ideas on how this can be achieved? So-far I have found this table explaining the current known functions; cmd | function 0x00a3 get current speed indicator of a fan (args: fan) 0x01a3 set speed of a fan (args: fan & speed) 0x02a3 get RPM of a fan (args: fan) 0x03a3 ??? (1 byte) 0x04a3 get nominal fan speed (2 args) 0x05a3 get fan tolerance speed (2 args) 0x10a3 get sensor temperature (1 arg: sensor#) 0x11a3 ??? 0x12a3 arg 0x0003=NBSVC-Query arg 0x0000=NBSVC-Clear arg 0x122=NBSVC-Start Trend arg 0x0100=NBSVC-Stop Trend arg 0x02??=NBSVC-Read 0x21a3 ??? (2 args: 1 byte (oder 0x16) + 1 byte) 0x22a3 get charger info (1 arg) 0x23a3 ??? (4 args: 2x 1 byte, 1xword, 1xdword) 0x24a3 get adaptor info status (1 arg oder 0x03) 0x30a3 ??? (no args) 0x31a3 ??? (no args) 0x32a3 ??? (no args) 0x33a3 ??? (no args) 0x36a3 get hotkey scancode list (args see diags) 0x37a3 ??? (no args) 0x40a3 get docking state (no args) 0xf0a3 ??? (2 args) 0xfea3 check SMBIOS version (1 arg) 0xffa3 check SMBIOS interface (returns:'DELLDIAG')

vitorafsr · Answer

Hi, I think we can work together in this implementation.

vitorafsr · Answer

I'm working in the Linux version of the driver. Let me ask a question: is the table about the code inside BIOS?

vitorafsr · Answer

I think in beginning the implementation of a driver to read the SMM table on Dell laptops, covering as much information as is available.

For now, nothing is done but I just have the intention. As Wipster87 posted some interesting code here, I found that is an opportunity to put plans in action.

So, I ask: do you want to be part of this development? Do you have any information besides the above table, because I don't have any; just the code from the i8k kernel module.

Tino Reichardt · Answer

Manual control of the fan on newer laptops like the Latitude e6530 can be done by using this tool: https://github.com/clopez/dellfan

The important defines are these:
#define DISABLE_BIOS_METHOD1 0x30a3
#define ENABLE_BIOS_METHOD1 0x31a3

Have fun ;-)

/milky

Tino Reichardt · Answer

Sorry for asking, but this tool is for Linux ?

Where I can found version for Windows ?

Sorry, I am not aware of any version of this new fan control for Windows... Maybe I will programm sometime a version... but this is not a promise ;)

Locked Topics – Laptops General

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