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Date:      Mon, 10 Jul 1995 18:52:24 -0700
From:      David Greenman <davidg@Root.COM>
To:        a00776@giant.mindlink.net (Toomas Losin)
Cc:        freebsd-questions@freebsd.org
Subject:   Re: 2.0.5 64 meg RAM limit? 
Message-ID:  <199507110152.SAA02421@corbin.Root.COM>
In-Reply-To: Your message of "Mon, 10 Jul 95 12:57:35 PDT." <m0sVOxU-0001pEC@giant.mindlink.net> 

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>I've got an interesting situation with our news server, running 2.0.5R.  It's
>just been expanded from 64 megs to 128 but the OS doesn't recognize the upper
>64.  To the best of my knowledge the BIOS is setup correctly.
>
>Is there a default 64 meg limit?  Can I specify an option to tell the kernel
>how much memory there is?  I've been digging through the source but nothing
>obvious jumps out at me (other than hard coding the amount - something I don't
>really want to do).

   FreeBSD gets the memory size from the 16bit K-bytes field in the BIOS RTC
memory. Since this is 16bits large, the maximum that it can represent is
65535K bytes (64MB). The only way to get FreeBSD to see more memory at the
moment is to add:

options "MAXMEM=131072"		(or whatever K-bytes you have)

   ...to your kernel config file.
   In the future FreeBSD will get the information in a different way (using
special BIOS calls at boot time), but there isn't sufficient space in the boot
blocks to do this and thus it first requires a 3 stage boot.

-DG



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