Re: Hunting the ahc boot-time panic

[Michael <macallan%netbsd.org@localhost>]

Hello,

On Sat, 22 Oct 2011 16:29:41 -0500 (CDT)
"John D. Baker" <jdbaker%mylinuxisp.com@localhost> wrote:

> An additional data point:
> 
> I have 3 B&W G3's, one with an Apple-branded Adaptec SCSI card and 2
> without any SCSI card.  I took one of the scsi-less machines, stuck a
> DELL-OEM'd AHA2940U/W card (w/PC BIOS ext. ROM) in it and it booted
> without problems (netboot) a kernel with no modifications (save for
> compiling in an 8x8 console font) and attached "ahc" to the card without
> complaint.

I think for devices with no OF ROM OF will just configure all BARs to sane 
values and leave it at that, while on devices with OF ROMs the ROM firmware 
determines what's configured and enabled and it may or may not ignore IO BARs.
I've seen similar behaviour on sparc64 - on some mach64 graphics cards the 
onboard firmware doesn't configure the IO BAR either. Technically not a problem 
- all registers are available in memory mapped BARs as well and on this 
hardware there is no real difference anyway, it all ends up memory mapped.

have fun
Michael