[LinuxBIOS] linuxbios Digest, Vol 31, Issue 85

Jonathan Sturges jonathansturges at yahoo.com
Tue Sep 18 13:43:50 CEST 2007

>> One thing I'd like to investigate as well is initializing the IRQ router in
>> LB.  I've seen some discussion about this in the past, and I've come to the
>> conclusion that for Geode GX1/CS5530 systems, it should be initialized in
>> LB rather than Linux.  It also seems like some LB ports do this, and others
>> do not.
>Linux does not know the CS5530 as an IRQ router. So it does not change 
>anything in its registers settings. For this chipset Linux relies on the 
>BIOS. Or you must patch the kernel. How to make LB fill in the routing 
>registers with usefull values?

Looking at newer Geode targets, some of the CS5536 systems seem to update the IRQ steering registers; see write_pirq_routing_table() in src/mainboard/artecgroup/dbe61/irq_tables.c.  I think that block of code could be adapted to the CS5530.  Is it pretty much understood that setting the IRQ steering registers within that function is the right place?


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