Date: Wed, 13 Mar 1996 14:49:15 -0500 (EST) From: "Marc G. Fournier" <scrappy@ki.net> To: Robin Lunn <robin@is.co.za> Cc: freebsd-bugs@freebsd.org Subject: Re: Kernel only sees 64Mb of RAM Message-ID: <Pine.BSF.3.91.960313144806.6527C-100000@ki.net> In-Reply-To: <199603131458.QAA22752@admin.is.co.za>
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On Wed, 13 Mar 1996, Robin Lunn wrote:
> Hi there,
>
> We've just installed FreeBSD 2.1.0-RELEASE onto a P-100 with 128Mb of ram.
> The kernel (as yet only the GENERIC kernel) only sees 64Mb of memory. I see
> no special definitions in the GENERIC kernel config file on my development
> system that would cause it to be limited as such.
>
> Have looked through the html handbook and FreeBSD 2.X FAQ on kernel
> configuration topics and see nothing of note. Will this problem be solved
> by a kernel compiled on that machine that has 128Mb of memory? Do I change
> some obscure value while under kernel -c before complete boot?
>
> Any help appreciated.
Look at section 8.6 of the FAQ:
8.6. I have 128 MB of RAM but it seems that the system use only the first 64
MB. What's going on ?
Due to the manner in which FreeBSD gets the memory size from the BIOS,
it can only detect 16 bits worth of Kbytes in size (65535 Kbytes =
64MB). If you have more than 64MB, FreeBSD will only see the first
64MB. To work around this problem, you need to use the kernel option
specified below. There is a way to get complete memory information
from the BIOS, but we don't have room in the bootblocks to do it.
Someday when lack of room in the bootblocks is fixed, we'll use the
extended BIOS functions to get the full memory information...but for
now we're stuck with the kernel option.
_________________________________________________________________
options "MAXMEM=<n>"
_________________________________________________________________
Where n is your memory in Kilobytes. For a 128 MB machine, you'd want
to use 131072
_________________________________________________________________
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