I am using a system based on an Abit NF7-M mobo with Award BIOS. I had noticed that I had a number of items allocated to the same IRQs, but this didn't seem to be much of a problem. Today, though, I lost Ethernet after connecting a USB Zip drive. I spent some time searching for the cause before I remembered the shared interrupts, umounted the drive, and Ethernet returned. The Bios shows nine IRQs available (3, 4, 5, 7, 10, 11, 12, 14, 15), but only five of these appear to be used. 14 and 15 are allocated to IDE, while 10 is shared by the VGA and USB controllers, 5 by the sound card and USB and 11 by my NIC, SMBus and USB again.

How can I re-allocate IRQs to avoid conflicts? The relevant sections of the lspci listing are given below.

Thanks,

Rob.

0000:00:02.0 USB Controller: nVidia Corporation nForce2 USB Controller (rev a4) (prog-if 10 [OHCI])
Subsystem: ABIT Computer Corp.: Unknown device 1c01
Flags: bus master, 66Mhz, fast devsel, latency 0, IRQ 5
Memory at ef002000 (32-bit, non-prefetchable)
Capabilities: [44] Power Management version 2

0000:00:06.0 Multimedia audio controller: nVidia Corporation nForce2 AC97 Audio Controler (MCP) (rev a1)
Subsystem: ABIT Computer Corp.: Unknown device 1c01
Flags: bus master, 66Mhz, fast devsel, latency 0, IRQ 5
I/O ports at d000
I/O ports at d400 [size=128]
Memory at ef000000 (32-bit, non-prefetchable) [size=4K]
Capabilities: [44] Power Management version 2

0000:00:02.1 USB Controller: nVidia Corporation nForce2 USB Controller (rev a4) (prog-if 10 [OHCI])
Subsystem: ABIT Computer Corp.: Unknown device 1c01
Flags: bus master, 66Mhz, fast devsel, latency 0, IRQ 10
Memory at ef003000 (32-bit, non-prefetchable)
Capabilities: [44] Power Management version 2

0000:02:00.0 VGA compatible controller: nVidia Corporation NV18 [GeForce4 MX - nForce GPU] (rev a3) (prog-if 00 [VGA])
Subsystem: ABIT Computer Corp.: Unknown device 1c01
Flags: bus master, 66Mhz, medium devsel, latency 32, IRQ 10
Memory at ec000000 (32-bit, non-prefetchable)
Memory at e4000000 (32-bit, prefetchable) [size=64M]
Memory at e8000000 (32-bit, prefetchable) [size=512K]
Capabilities: [60] Power Management version 2
Capabilities: [44] AGP version 2.0

0000:00:01.1 SMBus: nVidia Corporation nForce2 SMBus (MCP) (rev a2)
Subsystem: ABIT Computer Corp.: Unknown device 1c01
Flags: 66Mhz, fast devsel, IRQ 11 I/O ports at e000
Capabilities: [44] Power Management version 2

0000:00:02.2 USB Controller: nVidia Corporation nForce2 USB Controller (rev a4) (prog-if 20 [EHCI])
Subsystem: ABIT Computer Corp.: Unknown device 1c01
Flags: bus master, 66Mhz, fast devsel, latency 0, IRQ 11
Memory at ef004000 (32-bit, non-prefetchable)
Capabilities: [44] #0a [2080]
Capabilities: [80] Power Management version 2

0000:01:06.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)
Subsystem: Realtek Semiconductor Co., Ltd. RT8139
Flags: bus master, medium devsel, latency 32, IRQ 11 I/O ports at c000
Memory at ee000000 (32-bit, non-prefetchable) [size=256]
Capabilities: [50] Power Management version 2

I believe that you can not change IRQs through linux, or even windows for that matter, it is a BIOS issue and can be changed via the BIOS settings

Thanks for the reply. Actually, Windows 95 OSR2 and later can use "IRQ steering" to override the BIOS IRQ settings (settings can be altered through the device manager, so far as I remember - some time since I did it) . While my BIOS will allow me to reserve certain IRQs, it does not appear to provide a means to allocate them to specific devices, so I need to find a software-solution if at all possible.

Rob

I rechecked my mobo manual, and according to that I should be able to set IRQs for specific PCI slots. I did this, setting each one to one of the apparently unused IRQs, but lspci still shows the same result, so the OS does appear to be overriding the BIOS.