Hackery

Linux on Gigabyte GA-M59SLI-S5/S4 Motherboards

Thu 09 Aug 2007

We've been having a bit of trouble with these motherboards under linux recently. The two S4/S5 variants are basically identical except that the S5 has two Gbit ethernet ports where the S4 has only one, and the S5 has a couple of extra SATA connections - we've been using both variants. We chose these boards primarily because we wanted AM2 boards with multiple PCIe 16x slots to use with multiple displays.

We're running on the latest BIOS, and have tested various kernels from 2.6.9 up to about 2.6.19 so far - all evidence the same the same problems. Note that these are much more likely to be BIOS bugs, we think, than kernel problems.

The problems we're seeing are:

kernel panics on boot due to apic problems - we can workaround by specifying a 'noapic' kernel parameter at boot time

problems with IRQ 7 - we get the following message in the messages log soon after boot:

kernel: irq 7: nobody cared (try booting with the "irqpoll" option)
kernel:  [<c044aacb>] __report_bad_irq+0x2b/0x69
kernel:  [<c044acb8>] note_interrupt+0x1af/0x1e7
kernel:  [<c05700ba>] usb_hcd_irq+0x23/0x50
kernel:  [<c044a2ff>] handle_IRQ_event+0x23/0x49
kernel:  [<c044a3d8>] __do_IRQ+0xb3/0xe8
kernel:  [<c04063f4>] do_IRQ+0x93/0xae
kernel:  [<c040492e>] common_interrupt+0x1a/0x20
kernel:  [<c0402b98>] default_idle+0x0/0x59
kernel:  [<c0402bc9>] default_idle+0x31/0x59
kernel:  [<c0402c90>] cpu_idle+0x9f/0xb9
kernel:  =======================
kernel: handlers:
kernel: [<c0570097>] (usb_hcd_irq+0x0/0x50)
kernel: Disabling IRQ #7

after which IRQ 7 is disabled and whatever device is using IRQ 7 seems to fail intermittently or just behave strangely (and "irqpoll" would just cause hangs early in the boot process).

This second problem has been pretty annoying, and hard to diagnose because it would affect different devices on different machines depending on what bios settings were on and what slots devices were in. I spent a lot of time chasing weird nvidia video card hangs which we were blaming on the binary nvidia kernel module, which turned out to be this interrupt problem.

Similarly, if it was the sound device that happened to get that interrupt, you'd just get choppy or garbled sound out of your sound device, when other machines would be working flawlessly.

So after much pain, we've even managed to come up with a workaround: it turns out that IRQ 7 is the traditional LPT port interrupt - if you ensure the parallel port is turned on in the bios (we were religiously turning it off as unused!) it will grab IRQ 7 for itself and all your IRQ problems just go away.

Hope that saves someone else some pain ...