Date: Sat, 16 Nov 1996 17:44:50 -0800 From: David Greenman <dg@root.com> To: Erich Boleyn <erich@uruk.org> Cc: hackers@FreeBSD.org Subject: Re: Memory probe(s) in FreeBSD Message-ID: <199611170144.RAA17595@root.com> In-Reply-To: Your message of "Sat, 16 Nov 1996 16:04:37 PST." <E0vOuiz-00047c-00@uruk.org>
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>The situation is that FreeBSD does some weird stuff in >"i386/i386/machdep.c" which interferes with correct autodetection of >the amount of RAM installed. > >The existing bootloader checks the BIOS interfaces for lower and upper >memory, and pass that to the kernel. > >The kernel checks the RTC values and used to always ignore the values >passed by the bootloader. > >Currently, it does use the BIOS value passed by the bootloader for lower >memory, because it was discovered that this was necessary to get APM and >SMP code to work right. It still ignores the BIOS values for upper memory, >though. > >I would argue that the BIOS values should always be used, and the RTC >values simply ignored unless something specific (like the SMP probe) needs >them. I seem to recall that there was a problem with doing this on some systems, but since my memory is so vague, I'm inclined to agree with you. :-) It's probably that old FreeBSD bootblocks didn't pass in the BIOS information (via the bootinfo struct)...but this was so long ago that I don't think it matters anymore. Perhaps it should use the RTC numbers if the passed-in BIOS numbers are zero? -DG David Greenman Core-team/Principal Architect, The FreeBSD Project
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