On Mon, 2006-10-09 at 20:13 +0200, Mathias Friman wrote: > Hi list. > > I have a question regarding IRQ-assignment for an on-board card identified as an Intel 82801DB-ICH4. > > It is a crappy card, I know, and you probably ask yourselves why on earth I would want to put any effort > in configuring such sub-standard equipment. The question, fortunately, is a bit broader than that. I'm writing some swedish docs > on how to set up a Linux-system as a DAW, and see the need to do it thoroughly. :) > > As of now the card shares IRQ with the eth0-card, which isn't super if one is to set RT-prio 99 on it. > > Is there a simple way in setting a specific IRQ without the need for a super-BIOS that does it for you? Since I have > a laptop the option of shuffling the PCI-cards isn't really viable. :) > > I think I remember from my early days of kernel-hacking that it is possible to set IRQ with modprobe options, but it > was a while ago. I searched through the kernel tree in the /sound/pci/intel_8x0.c file to no avail. its basically not possible. PC architecture has changed quite a lot in the last few years, and AFAIK you can no longer get the kernel to change IRQ assignments. it seems stupid, i know, but i dug into this rather deeply a year or so back, and basically the kernel picks up the IO-APIC routings and does not modify them, even with the many flags that appear to be related to possibly modifying them :( there is a really cool perl script that actually analyses IO-APIC routings via the /proc filesystem, and it confirmed for me what i was worried about. if your BIOS doesn't allow it, you're out of luck *AFAIK*. if i am wrong, i will be happy to hear more, since i face similar issues on my laptop. --p
