Date: Tue, 6 May 2003 15:24:41 -0400 (EDT) From: agent dero <dero@bluhayz.homeunix.org> To: freebsd-performance@freebsd.org Subject: The magical missing 6 megabytes of mysterious RAM Message-ID: <20030506152406.P70768@bluhayz.homeunix.org>
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I don't beleive it can be BIOS sharing the system RAM with other devices, because my box that is in question has a 1MB Graphic card, and sits in the corner. Absolutely no work is done on the box physically. And I think the 1MB graphic card is enough to display BIOS and show the kernel and OS booting. (even if no monitor is attached) I am almost confident that is the kernel loaded into memory. I haven't seen much of a difference in real and availible memory between a custom kernel, and GENERIC. But, before the messages in /var/log/ are createde the FreeBSD boot manager must boot, and then it starts loading the kernel. So I am 99% sure it is the kernel being loaded into the active RAM. I will be able to test this more if I get a box with less RAM, that needs a good compiled kernel. But I think the issue should be put to rest with, the 6 "missing megabytes" being the kernel. (which must always be in the physical RAM) -thanks! --schnip-- > Yes and no. You can't reuse any memory used for page tables, > so that's "pure overhead". You also can't reuse any memory > that has not been marked as swappable. If you allocate memory > in the kernel, it will be permanently subtracted from the "avail" > (it just doesn't give you another message to the effect of any > chanes in "avail", because it would be printf'ing to the console > all the time, if it did), since kernel memory is allocated as > being type-stable. > --schnip to other message-- > I think you missed my point - I wasn't saying that FreeBSD is hiding > anything, nor was I talking about the "missing 6mb problem" directly. > You pretty much repeated my point though - "Since the BIOS is where > FreeBSD obtains the "real memory" number" - which is what I said, that > the BIOS takes the physical RAM, subtracts what it needs for devices > like video cards (that "borrow" from physical main memory), then reports > that result to any OS/Apps/etc that ask for it. That is why my system > doesn't show the 256Mb of memory it has in it, it shows something like > 224Mb (32Mb is set aside for the video card).. > > Unless I am totally missing your point this morning.. :)
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