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Date:      Mon, 07 Dec 1998 23:23:56 +0100
From:      Johan Karlsson <k@numeri.campus.luth.se>
To:        "Ron G. Minnich" <rminnich@Sarnoff.COM>
Cc:        hackers@FreeBSD.ORG
Subject:   Re: write combining memory on pci 
Message-ID:  <199812072223.XAA03758@numeri.campus.luth.se>
In-Reply-To: Your message of "Mon, 07 Dec 1998 15:48:33 EST." <Pine.SUN.3.91.981207154806.9378D-100000@terra> 

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At Mon, 07 Dec 1998 15:48:33 EST, "Ron G. Minnich" wrote:
>any good ideas on how to turn this on in 3.0 for a given memory address 
>range? 
>

This can be done using the MTRRs (Memory Type Range Registers) on a Ppro or 
PII.

There are some functions in i386/i386/pmap.c to read and write those 
registers. (I don't know if the registers are enabled by default)
For more info about the registers see
http://www.intel.com/design/pro/manuals
chapter 9 in "Intel Architecture Software Developer's Manual, Volume 3: System 
Programming Guide"

Usualy the BIOS sets these registers. You can screw up the memory management 
bad if you don't know what you are doing.

Take small steps :-)

/Johan K

-- 
Johan Karlsson		mailto:k@numeri.campus.luth.se
SWEDEN



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