Date: Wed, 11 Aug 1999 00:13:09 +0200 From: Gerald Heinig <gh046171@post.rwth-aachen.de> To: freebsd-sparc@freebsd.org Subject: Fwd: Boot PROM functions Message-ID: <37B0A3F5.3825ACE7@post.rwth-aachen.de>
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Hi folks, here's another piece of the puzzle that's fallen into place for me. I thought I'd share it :-) Gerald > Gerald Heinig wrote: > > > I have a question on Openboot Proms. As I understand it, when the > > machine boots, the Forth monitor checks all the installed devices, > > buses, cards etc and creates a device tree. It also calls each card's > > selftest routine (on SBus, at any rate). My question is: does this > > device tree get passed to the kernel which is then booted, or does the > > kernel do the whole thing over again for itself? > > I know that on Solaris x86 the monitor creates a device tree for all > > devices found and then passes the results of this probe to the program > > that is subsequently booted (normally the kernel, obviously). Presumably > > the Openboot monitor does this on Sparc machines too. Does it? > > > > I'll assume the answer to the question is yes. How, exactly, does this > > device tree get passed to the kernel? Are the data structures/parameter > > passing mechanisms documented anywhere? > > > > The OBP stuff is now an IEEE standard - IEEE 1275. Start at > http://playground.sun.com/1275/ for info on this. > > Solaris has an IEEE 1275 prom interface that the kernel uses to > make use of prom services. Among these is the facility to > receive the device tree as constructed by the prom. > The prom library used by the kernel is an IEEE 1275 > *implementation* - it's not documented itself. > > > Also, when the kernel boots ie. when the "Copyright Sun Microsystems > > .."etc etc stuff comes up with the little rotating bar, does the kernel > > use the prom routines to output its messages, or does it at this stage > > already use its own video drivers? > > > > Very early in boot we call prom_init() which sets the kernel > up to be able to use the prom services. One of the services > is prom_printf, and very early boot messages (and error messages > if any) are produced with this. > > Cheers > > Gavin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-sparc" in the body of the message
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