Date: Wed, 15 Oct 2003 15:58:29 +1000 From: Peter Grehan <grehan@freebsd.org> To: Alex Zepeda <zipzippy@sonic.net> Cc: freebsd-ppc@freebsd.org Subject: Re: FYI: rudimentary loader for ppcbug-based systems Message-ID: <3F8CE205.5CB0B9E0@freebsd.org> References: <E087F7025D7E494B8015119695CEDB4C01972204@zpl02exm01.mpsc.mot.com> <3F8CAFAE.6260CFCF@freebsd.org> <20031015044706.GA787@blarf.homeip.net>
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Hi Alex, > > Clean interfaces would be the best. The ultimate is a single kernel that could > > run on all combinations of processor and firmware, the true GENERIC, but I'm not > > sure if that's possible. > > I think this is the wrong way to go. IMO, NetBSD has the right idea. Treat each > PPC platform as a truely independent platform. They've got sys/arch/powerpc for > the truly generic stuff. Userspace is unnecessarily replicated for each of those platforms. There's a lot more differences between a lot of FreeBSD/alpha platforms than there is for the different NetBSD PPC platforms. Even properly supporting CPU differences between PPC models on the same h/w platform is perhaps more work than being able to support h/w differences in the same kernel. FreeBSD has a number of features to ease this, such as a common 3rd stage loader, devfs, etc. As I said, it may not be possible, but there's no point in writing it off from the start. > This allows them to support stuff like the BeBox, MacPPC, various IBM boxen, etc. > > This would be, IMO, similar to how FreeBSD handles the pc98 case... and the > current powerpc stuff would be split up into MI (sys/powerpc) and MD (sys/powermac > or sys/macppc maybe) portions. That's somewhat historical, and there's no need to go down that path unless necessary. > Darwin, and perhaps LinuxPPC, apparently handles the device enumeration and such > without openfirware (actually BootX more or less renders any OF stubs unuseable). > This is perhaps a nice goal, but IMO, it would be better to at least get > everything working *with* OFW. This is of course easier with the new-world > machines which have reasonable versions of OF. Darwin and LinuxPPC still use OpenFirmware - Linux pulls in a copy at boot-time before blowing it away so the info is still there. FWIW, I plan on getting things useable on NewWorld before I start out on my original goal of getting Free up and running on embedded PPC platforms. later, Peter.
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