From owner-freebsd-atm Wed Jan 17 16:52:48 2001 Delivered-To: freebsd-atm@freebsd.org Received: from mail-blue.research.att.com (mail-blue.research.att.com [135.207.30.102]) by hub.freebsd.org (Postfix) with ESMTP id 5C6DB37B401 for ; Wed, 17 Jan 2001 16:52:31 -0800 (PST) Received: from alliance.research.att.com (alliance.research.att.com [135.207.26.26]) by mail-blue.research.att.com (Postfix) with ESMTP id AE2114CE7A; Wed, 17 Jan 2001 19:52:26 -0500 (EST) Received: from chips-ha.research.att.com (chips-ha.research.att.com [135.207.27.139]) by alliance.research.att.com (8.8.7/8.8.7) with ESMTP id TAA02849; Wed, 17 Jan 2001 19:52:18 -0500 (EST) Received: (from chuck@localhost) by chips-ha.research.att.com (SGI-8.9.3/8.8.5) id TAA62786; Wed, 17 Jan 2001 19:52:17 -0500 (EST) Date: Wed, 17 Jan 2001 19:52:17 -0500 From: Chuck Cranor To: Richard Hodges Cc: Mike Tancsa , freebsd-atm@FreeBSD.ORG Subject: Re: ATM under 4.x STABLE ? Message-ID: <20010117195217.A2037890@chips.research.att.com> References: <5.0.1.4.0.20010116114713.033bd7c0@marble.sentex.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from rh@matriplex.com on Tue, Jan 16, 2001 at 09:18:43AM -0800 Organization: AT&T Labs-Research Sender: owner-freebsd-atm@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Tue, Jan 16, 2001 at 09:18:43AM -0800, Richard Hodges wrote: > On Tue, 16 Jan 2001, Mike Tancsa wrote: > > en0: mem 0xfe000000-0xfe3fffff irq 11 at > > device 8.0 on pci1 > > en0: unexpected timeout in rx DMA test > > en0: WARNING: DMA test detects a broken PCI chipset! > > trying to work around the problem... but if this doesn't > > work for you, you'd better switch to a newer motherboard. en0: maximum DMA burst length = 64 bytes (must align) > Ouch! Looking at /usr/src/sys/dev/en/midway.c I see some very interesting > notes about broken DMA in the Efficient card (but not Adaptec). The > driver is supposed to work around that, though. Your DMA message above > seems to refer to the chipset not being able to handle "misaligned 64 > byte DMA", which might not be a major problem, but just might reduce > the performance. > Of course, the real authority is Chuck Cranor himself... hi- Adaptec totally redid the DMA interface to this card and it works great. the Efficient version is more painful to program and gets some things wrong. the card init code does some extensive testing to find the best mode that will work for the card. Mike's system supports large DMA bursts (64 byte), but the starting address of the buffer must be aligned to a 64 byte boundary (that's why it says "(must align)" and printed the warning). i don't think this will be a major problem (if you've got a large DMA, you can break it up into chunks to get the needed 64 byte alignment... the driver will do this for you). chuck -- Chuck Cranor Senior Technical Staff Member, AT&T Labs-Research Room B135, 180 Park Ave, Florham Park NJ, 07932 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-atm" in the body of the message