Date:	Mon, 4 Jan 1999 09:43:36 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	Bob Babcock <wssddc AT gis DOT net>
cc:	djgpp AT delorie DOT com
Subject:	Re: Check cache beyond 64MB with djgpp?
In-Reply-To:	<n3jaf00m11w.fsf@shell.gis.net>
Message-ID:	<Pine.SUN.3.91.990104094309.12525G-100000@is>
MIME-Version:	1.0
Reply-To:	djgpp AT delorie DOT com

On 3 Jan 1999, Bob Babcock wrote:

> Has anyone written a cache-checking program using the djgpp functions such as
> __djgpp_map_physical_memory()?  I've seen several programs which will tell
> you the size of your L1 and L2 caches, but none seem to want to test beyond
> 64MB.

I believe this is a wrong approach.  __djgpp_map_physical_memory goes
through the DPMI server, and many DPMI servers won't let you access
more than 64MB of memory.  (See section 3.10 of the DJGPP FAQ list for
more on this.)

What you need is to access raw extended memory using a physical
(as opposed to logical) address.  It strikes me that the easiest way
to accomplish this would be to write a real-mode program that issues
XMS calls to allocate buffers in the extended memory, and moves data
between them.

Another possibility would be to write a DJGPP program that issues XMS
calls like above, and run it in plain DOS mode (no Windows) with
EMM386 installed as a memory manager.

The above is not tested at all, so caveat emptor.

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