[LinuxBIOS] Building an irq table - Help

Uwe Hermann uwe at hermann-uwe.de
Fri Oct 19 18:36:59 CEST 2007

On Thu, Oct 18, 2007 at 11:01:59PM -0400, Corey Osgood wrote:
> I would mark those irq tables as broken and use acpi routing. You can
> dump the factory acpi tables using acpidump (or cat /proc/acpi/dsdt >
> somefile), then decompile them with iasl. Once you do that, you can look
> through them for "(_PRT)", which should be the routing table. At that
> point, if the tables are simple enough, you can just pull those out, or
> if they're deeply integrated you can use the entire dsdt. Note that
> there may be some legal issues with redistribution of acpi tables,
> although the linux acpi project (on sourceforge) distributes them
> regularly, so I'm not sure where the problem lies.

I'm not sure either (and I'm not a lawyer of course), but I'd refraid
from distributing whole ACPI tables + AML code gathered via acpidump
(my guess is that the AML code is the bigger problem, as it's "code"
whereas the static tables are just a bunch of numbers/data items in
a simple list, more or less).

Not sure if it's a problem indeed, but we shouldn't take the risk if
we don't have to.

The alternative is to either have the _user_ use acpidump on his system
(and we provide a generic ACPI framework which can deal with acpidump
output, more on that later). This is similar to the VGA blob approach.

The other possibility is to construct a valid irq_table.c with the help
of the _PRT info (no need for ACPI if all you want is a working irq_table.c).

Or, you can try to fix up irq_table.c with the help of the method
Juergen described in http://linuxbios.org/Creating_Valid_IRQ_Tables,
where I'm pretty much 100% sure that there's _no_ legal problem
involved whatsoever.

http://www.hermann-uwe.de  | http://www.holsham-traders.de
http://www.crazy-hacks.org | http://www.unmaintained-free-software.org
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