Date: Mon, 01 Jun 1998 00:43:51 -0700 From: Jason Thorpe <thorpej@nas.nasa.gov> To: Curt Sampson <cjs@portal.ca> Cc: Doug Rabson <dfr@nlsystems.com>, Mike Smith <mike@smith.net.au>, hackers@FreeBSD.ORG Subject: Re: AlphaBIOS documentation Message-ID: <199806010743.AAA20008@lestat.nas.nasa.gov>
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On Mon, 1 Jun 1998 00:24:23 -0700 (PDT) Curt Sampson <cjs@portal.ca> wrote: > There's plenty of device driver source code in Linux and NetBSD, too. :-) > > My point is, every time a new type of Alpha comes along, you have > to write new PALcode and compile it in to the boot loader. This is > not really all that different than having to write and compile in > a new device driver every time a new device comes along. Not really. Once you have working PALcode for a given platform, you never have to touch it again. This is not true with drivers, which may need modification for the next rev of a device. Also, the VAST majority of PALcode is common from one platform to another. Usually, the only differences are in the interrupt routing code, and these differences are usually very minor (esp. between same implementation revs, e.g. two 21064-based systems or two 21164-based systems). The other main difference is in the code that builds the CPU logout area; this code usually copies platform-specific core logic registers. However, this will be the same between two platforms which use the same core logic chipset (e.g. the AlphaStation 500 and the AlphaPC 164, both of which use an ALCOR2). However, it is worth noting that the MILO PALcode doesn't actually work very well, and doesn't implement an interface completely compatible with the OSF/1 PALcode shipped with the SRM (logout area is different, for example, and some exception vectors are different). In other words, I wouldn't exactly recommend using the MILO PALcode as a base. Jason R. Thorpe thorpej@nas.nasa.gov NASA Ames Research Center Home: +1 408 866 1912 NAS: M/S 258-5 Work: +1 650 604 0935 Moffett Field, CA 94035 Pager: +1 650 428 6939 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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