27 Nov
2005
27 Nov
'05
9:34 a.m.
On Sat, 2005-11-26 at 17:40 -0800, Mark Knecht wrote:
Changing interrupt priorities of internal devices on a
laptop is not
possible. The devices are on the motherboard and are hard wired to
specific inputs on the PIC. You cannot change them at all.
i am not sure that this is strictly true. my impression of modern intel-
based architecture is that the inputs to the (A)PIC do not map
deterministically to IRQ lines feeding the CPU. the (A)PIC and its
cousins can be programmed to do many different things. the problem with
laptops is generally that they come with a BIOS that offers no options
to "reprogram" the (A)PIC, and then you boot into a kernel that
generally seems to want to leave this stuff alone. this is increasingly
the case on non-laptops as well, which is quite depressing.
i wrote a little perl script sometime this year or last to dump the PIC
routings. it was quite instructional :)
--p