Date: Fri, 06 Oct 1995 03:26:06 -0700 From: David Greenman <davidg@Root.COM> To: Julian Elischer <julian@ref.tfs.com> Cc: elh_fbsd@spnet.com, questions@freebsd.org, elh@spnet.com Subject: Re: kernel options for > 64mby Message-ID: <199510061026.DAA00423@corbin.Root.COM> In-Reply-To: Your message of "Fri, 06 Oct 95 03:21:23 PDT." <199510061021.DAA07412@ref.tfs.com>
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>> >> > i hate to ask a question that has been asked and >> > answered a few times before, but... >> > >> > what kernel options/files require modification for >> > a machine with > 64mby? >> >> add this to your kerel config file: >> >> options "MAXMEM=131072" >> >> >> ...where "131072" is the size of memory in Kbytes - in the above example, this >> would be 128MB (128*1024). Someday I'll try to make this a bit more automatic. >> >Under OSF I made it go hunting if it thought that there might be more.. >basically, if the BIOS says 64MB (well I use >=63MB as I don't trust Bios's) >I do memory tests upwards till I start getting failures.. > >The trick is to do this BEFORE YOU SWITCH ON PAGING >so that you don't get pagefaults.. > >I could send you the code but it PROBABLY doesn't apply directly, >and you'd probably do better implimenting it yourself once you've >heard the idea of how I did it.. Whether or not you have paging enabled isn't a problem. The problem is that some (Compaq) motherboards will happily generate an NMI if the parity isn't read back correctly for non-existent memory. The only correct way to do this is to get the correct size by asking the BIOS in the correct way for it. We have code that will do this, but it bloats our bootblocks to the point that they won't fit anymore. -DG
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