From owner-freebsd-alpha Wed Oct 4 15:47:33 2000 Delivered-To: freebsd-alpha@freebsd.org Received: from feral.com (feral.com [192.67.166.1]) by hub.freebsd.org (Postfix) with ESMTP id 9D30537B502 for ; Wed, 4 Oct 2000 15:47:31 -0700 (PDT) Received: from beppo (beppo [192.67.166.79]) by feral.com (8.9.3/8.9.3) with ESMTP id PAA01760; Wed, 4 Oct 2000 15:47:26 -0700 Date: Wed, 4 Oct 2000 15:47:25 -0700 (PDT) From: Matthew Jacob Reply-To: mjacob@feral.com To: Doug Rabson Cc: Wilko Bulte , FreeBSD-alpha mailing list Subject: Re: max memory on Alpha? In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-alpha@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Wed, 4 Oct 2000, Doug Rabson wrote: > On Tue, 3 Oct 2000, Wilko Bulte wrote: > > > What is the currently max supported memory size on Alpha? 2Gb maybe? > > Or will 4Gb also be OK? > > > > Reason for asking is that I want to try a AS8400 who is equipped > > with 3x 4Gb memory module. > > Currently we are limited to 1Gb or 2Gb, depending on the platform. The > tsunami driver uses a 2Gb window for dma and I think AS4x00 and AS8x00 > also support 2Gb. > > Supporting more memory requires that all dma capable hardware is the > busdma interface in its drivers. Given that, someone needs to write a > small amount of code in busdma_machdep.c to either bounce transfers down > to the 2Gb range or to use the sgmap to map the transfers into a reachable > place. Some SGMAP stuff is initialized- but you're right about dma-busifying. I'm about ready to shove an extra 512 MB memory module into an 8200 to take it to 2.5GB just to see what'll happen. -matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message