Thanks for the acpidump. It looks like OSI(Linux) is a NOP on this box. so you shouldn't notice any difference between acpi_osi=Linux and acpi_osi=!Linux. -Len The write to OSYS is a NOP, as it quickly gets over-written. Looks like Acer writes the value 0x70 the (debug?) port at 0xB3, but otherwise OSI(Linux) will have no effect on this system. If (CondRefOf (_OSI, Local0)) { If (_OSI ("Linux")) { Store (0x03E8, OSYS) OSMI (0x70) } If (_OSI ("Windows 2006")) { Store (0x07D6, OSYS) } Else { Store (0x07D1, OSYS) } } Else { Store (0x07D0, OSYS) } ... OperationRegion (SMIO, SystemIO, 0xB2, 0x02) Field (SMIO, ByteAcc, NoLock, Preserve) { APMC, 8, APMD, 8 } ... Method (OSMI, 1, NotSerialized) { Store (Arg0, APMD) Store (0xB2, APMC) Stall (0xFF) Stall (0xFF) Stall (0xFF) Stall (0xFF) Stall (0xFF) Stall (0xFF) } - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html