Trying to understand initsenses and pci_irq_table
Richard Danter
richard.danter at ntlworld.com
Tue Nov 22 21:20:34 EST 2005
Hi all,
I am trying to port a 2.6.14.2 kernel to a 74xx/107 board and am having
some problems which I think may be interrupt related. I have based my
board support on the Sandpoint but realise that I do not really
understand the initsenses or pci_irq_table structures and was hoping
someone could either explain it or point me in the direction of some docs.
So far the kernel does boot and mount a NFS root filesystem, but crashes
soon after. Whilst it boots the serial is very slow. It is at 9600 baud
as expected, but it seems the characters are being spaced out in time
which makes me think the serial is running in a polled mode rather than
interrupt driven.
The board is very simple. There are several versions and the one I am
working on now has a 7400 CPU, a 107 mem controller, a couple of PCI
slots, serial port and some LED's.
Interrupts A, B, C and D from the PCI slots are connected to IRQ 0..3 on
the 107. The serial port chip (16550 compatible) is wired directly to
IRQ 4. There are no other PIC's or any other logic to confuse things.
U-Boot is running just fine and shows the following when I use the "pci"
command:
Scanning PCI devices on bus 0
BusDevFun VendorId DeviceId Device Class Sub-Class
_____________________________________________________________
00.00.00 0x1057 0x0004 Bridge device 0x00
00.10.00 0x8086 0x1030 Network controller 0x00
00.12.00 0x1011 0x0026 Bridge device 0x04
How should these be mapped with the structures in the kernel?
The fact that NFS seems to be working and that the network card
(EEPRO100) says it is using IRQ 16 is just pure luck I think!
The kernel crashes after starting init. I see some random characters on
the serial and then nothing. Looking in the log buffer via JTAG I can
see that the init process exited with signal 11. I assume this is
unrelated to the above, but any suggestions where I should look?
Many thanks,
Rich
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