Date: Wed, 27 Feb 2008 07:34:48 -0600 From: Jeff Isaac <cineveggie.lists@gmail.com> To: freebsd-amd64@freebsd.org Subject: Re: "freebsd-amd64" Message-ID: <443D814E-04F3-411C-9DF9-E799A39FAEB3@gmail.com> In-Reply-To: <E1JULcb-0001Er-9m@dilbert.ticketswitch.com> References: <E1JULcb-0001Er-9m@dilbert.ticketswitch.com>
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On Feb 27, 2008, at 6:42 AM, Pete French wrote: > "So the SMAP problem is that in the one BIOS I looked at, the SMAP > BIOS call > only works from real mode. Even if invoked from virtual 86 mode, > the BIOS > call fails. FreeBSD only calls the BIOS SMAP call from virtual 86 > mode both > in the loader and in the i386 kernel. The fix is quite complicated > and > involves rewriting the boot code to invoke BIOS calls from real mode > rather > than virtual 86 mode." Forgive me if this has already been asked, but I'm in the process of trying to teach myself some of the basics for the loader and boot, etc... on the powerpc port. I realize that this is platform specific and probably has zero bearing on anything I code specifically (since I'll have firmware to doodle with, not BIOS), BUT, from a general knowledge perspective, what advantages does virtual 86 mode have over real mode? Essentially, why did the FreeBSD project choose the virtual implementation? More portable? Easier to write? None of the above? Thanks! :) - Jeff
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