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List:       9fans
Subject:    Re: [9fans] 3c509b troubles
From:       lucio () proxima ! alt ! za
Date:       2008-08-30 5:05:30
Message-ID: dab04424b8848545eb53dfb563094703 () proxima ! alt ! za
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> heh. geez am i dopey. the problem was my misunderstanding of what the
> irq=xx parts in plan9.ini do. bios decides the irq, plan9.ini tells
> the kernel what the bios decided. that's my isa card mantra from now
> on

I was going to suggest you base your configuration on what OpenBSD
determines.  It I remember right (I have a few 3Com cards I treasure)
they all allowed an autoconfiguration that predates PnP but resembles
it somehow: identify the autoconfiguration port and wiggle it to tell
the card where to enable IRQ, I/O and possibly DMA.

Plan 9 may have had an issue with the configuration port.  ISA has a
big issue with shared IRQs: IBM engineered the IRQs to be
level-triggered and active low TTLs, so an inactive card would mask
any other card reporting an interrupt on the same line.  I was told
some of these decisions (the choice of 8250s instead of 8251s for
serial communication, for example) were intentional.

OK, there I go showing off :-) Just in case people think I'm still the
fourteen year old weenie in the "face" archive and get shocked when I
pitch up in Volos :-)

++L


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