Date: Fri, 11 Apr 1997 09:39:18 +0200 (MET DST) From: Guido van Rooij <guido@gvr.win.tue.nl> To: bde@zeta.org.au (Bruce Evans) Cc: peter@freefall.freebsd.org, cvs-all@freefall.freebsd.org, CVS-committers@freefall.freebsd.org, cvs-sys@freefall.freebsd.org Subject: Re: cvs commit: src/sys/i386/i386 genassym.c machdep.c trap.c src/sys/i386/include pcb.h Message-ID: <199704110739.JAA06258@gvr.win.tue.nl> In-Reply-To: <199704101705.DAA13021@godzilla.zeta.org.au> from Bruce Evans at "Apr 11, 97 03:05:12 am"
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Bruce Evans wrote: > >> This change makes VM86 mode harder, but the following commits will remove > >> a lot of constraints for the VM86 system, including the possibility of > >> extending the pcb for an IO port map etc. > > > >Yes! Finally get rid of the old /dev/io hack ;-) > > It would mainly make things more complicated and cost more. Accesses > through the port map cost 20 cycles extra. There would be up to 64K of > ports to manage. Who knows where the DMA ports (if any) on new video > cards are? The extra cost is only for ppl using the io port map. As far as I understand it this map is optional. When non-present you don't have to fiddle with it. So the performance penalty is only for those ppl. -Guido
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