From owner-freebsd-hackers Thu Jun 3 8:28:51 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from gw-nl3.philips.com (gw-nl3.philips.com [192.68.44.35]) by hub.freebsd.org (Postfix) with ESMTP id A938C14D1F for ; Thu, 3 Jun 1999 08:28:47 -0700 (PDT) (envelope-from Jos.Backus@nl.origin-it.com) Received: from smtprelay-nl1.philips.com (localhost.philips.com [127.0.0.1]) by gw-nl3.philips.com with ESMTP id RAA17201 for ; Thu, 3 Jun 1999 17:28:46 +0200 (MEST) (envelope-from Jos.Backus@nl.origin-it.com) Received: from smtprelay-eur1.philips.com(130.139.36.3) by gw-nl3.philips.com via mwrap (4.0a) id xma017197; Thu, 3 Jun 99 17:28:46 +0200 Received: from hal.mpn.cp.philips.com (hal.mpn.cp.philips.com [130.139.64.195]) by smtprelay-nl1.philips.com (8.9.3/8.8.5-1.2.2m-19990317) with SMTP id RAA23017 for ; Thu, 3 Jun 1999 17:28:45 +0200 (MET DST) Received: (qmail 21398 invoked by uid 666); 3 Jun 1999 15:29:07 -0000 Date: Thu, 3 Jun 1999 17:29:07 +0200 From: Jos Backus To: Zhihui Zhang Cc: freebsd-hackers@freebsd.org Subject: Re: The choice of MAXPHYS Message-ID: <19990603172907.A20792@hal.mpn.cp.philips.com> Reply-To: Jos Backus References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.95.5i In-Reply-To: ; from Zhihui Zhang on Thu, Jun 03, 1999 at 10:40:10AM -0400 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Thu, Jun 03, 1999 at 10:40:10AM -0400, Zhihui Zhang wrote: > The value of MAXPHYS is chosen to be 64K for the maximum raw I/O transfer > size. I am wondering why it is not set larger. Just a guess: maybe this has something to do with DMA address counters on ISA cards being 16 bit? (ducks) Or is this total nonsense? :-) -- Jos Backus _/ _/_/_/ "Reliability means never _/ _/ _/ having to say you're sorry." _/ _/_/_/ -- D. J. Bernstein _/ _/ _/ _/ Jos.Backus@nl.origin-it.com _/_/ _/_/_/ use Std::Disclaimer; To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message