Date: Sun, 11 Jan 1998 20:39:45 -0800 (PST) From: Jason Evans <jasone@canonware.com> To: Ian Logan <ian@nmsu.edu> Cc: freebsd-sparc@FreeBSD.ORG, Chris Toshok <toshok@hungry.com> Subject: Re: How UltraAX boots Message-ID: <Pine.BSF.3.96.980111122603.533P-100000@mozart.canonware.com> In-Reply-To: <34B8FF49.42027ECC@nmsu.edu>
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On Sun, 11 Jan 1998, Ian Logan wrote: > Jason Evans wrote: > > > We're going to be facing a big bang problem as far as booting goes. In > > order to get a serial console working, it looks like we'll have to have > > the UPA, PCI, and EBus code working, in addition to serial code (just need > > to port the serial code). So, we'll pretty much have to make the whole > > motherboard work all at once, unless we can route the console through OBP > > (seems unlikely, or at least problematic). Yuck. > > Actually it shouldn't be too bad :) OBP has functions that work almost > like printf and they automaticly send their output to whatever output > device is set in the enviroment variables, I believe they are > output-device and input-device. For example, the startup code in > sys/sparc/sparc/locore.s uses these functions to printout a message if > it's running on a unsupported CPU. > > In Linux they wrote a little library of interface functions for the > prom, so we could do the same thing. Then just pick our output function > based on a #define. > ie. > #if defined(PROM_DEBUG) > prom_printf(...) > #else > printf(...) > #endif > > Of course this is still pretty ugly, but it could be a lot worse. This will be good. We'll probably have to be careful not to probe for the serial port if we're using OBP for the console, but that's just a minor detail in comparison. =) Jason Jason Evans Email: [jasone@canonware.com] Home phone: [(650) 856-8204] Work phone: [(408) 774-8007] Quote: ["Invention is 1% inspiration, 99% perspiration" - Thomas Edison]
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