Woozy Numbat on my notebook, part 1
I ran into a problem while trying to upgrade to Linux 2.6.10
on my notebook
didn't find any soundcards during boot,
although it should (2.6.9 did).
0000:00:1f.5 Multimedia audio controller: Intel Corp. 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Audio Controller (rev 03)
After searching through the kernel source and trying various other things,
including building the driver as module, loading with special parameters,
forced loading, many ugly hacks...
Needless to say, none of my approaches
lead to a working soundcard. After a while I recognized that with 2.6.10,
my parport device got an IRQ assigned to it, IRQ 7. My soundcard also wants
to occupy this IRQ but that shouldn't be the problem, I thought, because in
times, where we have IRQ sharing and request_irq's SA_SHIRQ parameter, two
devices per IRQ could easily be done.
Anyhow, I rebooted to view the IRQ-table in 2.6.9 but I didn't see the
parport device listed there. This was the time, when I knew, that I know
absolutely not enough about the parport implementation in the linux kernel.
After reading the parport documentation, everything was much clearer to me.
parport doesn't need an interrupt, to work properly. 2.6.10 was the first
kernel, that assigned one to it - maybe because of the new PNP ACPI feature?
Appending one additional parameter to the kernel's cmdline solved the problem
by restoring the old behaviour: not assigning an interrupt to the parport driver.
LILO: 2.6.10 parport=0x378,-1
The -1 means, that no IRQ should be assigned to the parport driver. Now everything is fine:
0: 3864839 XT-PIC timer
1: 11674 XT-PIC i8042
2: 0 XT-PIC cascade
4: 1 XT-PIC ehci_hcd
5: 120838 XT-PIC yenta, uhci_hcd, uhci_hcd, uhci_hcd, eth0, eth1
7: 0 XT-PIC snd-intel8x0
9: 7641 XT-PIC acpi
12: 95168 XT-PIC i8042
14: 24773 XT-PIC ide0
15: 13 XT-PIC ide1
There are also other issues with 2.6.10 on my system, but that's another
story, maybe in another entry...