Date: Fri, 02 Jul 1999 18:12:35 -0700 From: Mike Smith <mike@smith.net.au> To: Greg Lehey <grog@lemis.com> Cc: Mike Smith <mike@smith.net.au>, Mike Smith <msmith@FreeBSD.org>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/i386/i386 machdep.c Message-ID: <199907030112.SAA02288@dingo.cdrom.com> In-Reply-To: Your message of "Sat, 03 Jul 1999 10:31:11 %2B0930." <19990703103111.F87392@freebie.lemis.com>
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> On Friday, 2 July 1999 at 17:39:31 -0700, Mike Smith wrote: > >> On Friday, 2 July 1999 at 13:33:35 -0700, Mike Smith wrote: > >>> msmith 1999/07/02 13:33:35 PDT > >>> > >>> Modified files: > >>> sys/i386/i386 machdep.c > >>> Log: > >>> Lightly overhaul the memory sizing code again. > >>> > >>> - The kernel environment variable 'hw.physmem' can be used to set the > >>> amount of physical memory space, based at 0, that FreeBSD will use. > >>> Any memory detected over this limit is ignored. Documentation for > >>> this is available under 'help set tunables' in the loader. > >>> > >>> - In the case where system memory size can't be accurately determined, > >>> hw.physmem is used as a best-guess memory size, but speculative > >>> probing will be used to determine actual memory size if any of the > >>> guesses or hints are 16M or more. > >> > >> Don't these two paragraphs contradict each other? > > > > No. In the first case, if more than hw.physmem is detected, any excess > > is ignored. In the second, if it's not possible to determine how much > > memory there is, hw.physmem is used as a working guess in conjunction > > with a speculative probe. > > So depending on factors beyond your control, it either limits the size > of memory used, or it doesn't? No; the system that you use it on is a factor under your control. > It seems that you could have found a less confusing and more > controllable way to do it. I guess you're not feeling very constructive today. There are a number of sets of existing behaviour that I didn't want to change just yet, since I wanted some more cycles on this code first. There's all sorts of silliness regarding the 16M and 64M points that don't yet quite add up. Ultimately, hw.physmem will always mean "do not ever use more memory than this (but if you can't work it out yourself, try to find this much)". -- \\ The mind's the standard \\ Mike Smith \\ of the man. \\ msmith@freebsd.org \\ -- Joseph Merrick \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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