Date: Thu, 15 May 1997 19:34:36 -0400 (EDT) From: Andrew Gallatin <gallatin@CS.Duke.EDU> To: Curt Sampson <cjs@portal.ca> Cc: freebsd-alpha@FreeBSD.ORG Subject: Re: Alpha questions.. Message-ID: <199705152334.TAA03950@hurricane.cs.duke.edu> In-Reply-To: <Pine.NEB.3.93.970515154142.408n-100000@gnostic.cynic.net> References: <E0wS8mH-0001Pj-00@rover.village.org> <Pine.NEB.3.93.970515154142.408n-100000@gnostic.cynic.net>
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Curt Sampson writes: > On Thu, 15 May 1997, Warner Losh wrote: > > > The key here is that we can generally load in our own PALs (ala milo) > > and then it won't be an issue. > > No. You'll just have a heck of a lot of different PALcode versions > to write. From looking at the source to MILO, it appears that they > have at least six different versions of the PALcode for different > machines, and a MILO compiled with any particular version will only > work on matching machines, nothing else. Right. *Exactly* like SRM. There's a unique version of the SRM console for all the machines it supports, partially because each machine requires a different version of the OSF Palcode. > Whereas, if you use the > OSF1 PALcode, you have to go to the effort of duplicating PALcode > only on those machines that don't support OSF1 PALcode at all, > rather than all new Alpha machines. I think the PALcode included in Milo was obtained directly from Digital by Milo's author. From looking at the copyright's & RCS id's on it, it would appear to really be the OSF palcode. I think we're again blurring the distinction between console software and PALcode, so here's the executive summary of what I said yesterday. Sorry to sound like a broken record ;-) SRM & Milo are each different types of console software. They exist to, among other things, to initialize the hardware (build HWRPB, size memory, etc), load-up the PALcode for the OS to use & bootstrap the OS. Once the OS is fully up & running, the console software is irrelevant. PALcode is used to mask differences between different types of hardware, and to present to the OS a fairly uniform interface across different alpha platforms for the purpose of things like exception & trap handling, interrupt dispatching, IPL setting, context-swapping, emulation of instructions not present on all platforms, etc. The PALcode is used in conjunction with the OS. As far as I can tell, Digital UNIX, NetBSD, and Linux all use the OSF PALcode. NT appears to use its own, which has probably been munged somehow for use by a 32-bit OS. Drew ------------------------------------------------------------------------------ Andrew Gallatin http://www.cs.duke.edu/~gallatin Duke University Email: gallatin@cs.duke.edu Department of Computer Science Phone: (919) 660-6590home | help
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