From mboxrd@z Thu Jan 1 00:00:00 1970 From: ron minnich To: 9fans@cse.psu.edu Subject: Re: [9fans] loading plan 9 directly from linuxbios In-Reply-To: <8c06d2c68998f806c7a0cb8b7fdcd2f9@caldo.demon.co.uk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Date: Wed, 29 Oct 2003 09:16:38 -0700 Topicbox-Message-UUID: 7a9359aa-eacc-11e9-9e20-41e7f4b1d025 On Wed, 29 Oct 2003, Charles Forsyth wrote: > the deeper problem is that (as i understand it) you're entering the code > in real mode, which is of course quite unreal. in that case you'll need > to do what 9load does in l.s (using x16.h) to write the real mode code, > because 8a/8l isn't very good at 16-bit code (though 8l could make it > easier, with some as yet unquantified amount of work). Entering from linuxbios and also from 9load, you are entering plan 9 in 32-bit protected mode with the gdt set up. The issue from linuxbios is that the gdt is not Plan9-compatible. I think it is probably good hygiene for plan 9 to be able to operate under other loaders than 9load, so overall it is probably good for Plan 9 to assume - machine is in protected mode (but no paging turned on) - gdt is maybe right, but maybe wrong - lgdt can be used in 32-bit mode - plan 9 should reload the gdt in l.s, 32-bit instructions, before it sets up paging ron