From owner-freebsd-hackers Thu May 2 15:13:14 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id PAA00537 for hackers-outgoing; Thu, 2 May 1996 15:13:14 -0700 (PDT) Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id PAA00521 for ; Thu, 2 May 1996 15:13:05 -0700 (PDT) Received: from sax.sax.de by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id AAA07308; Fri, 3 May 1996 00:12:23 +0200 Received: by sax.sax.de (8.6.11/8.6.12-s1) with UUCP id AAA01698; Fri, 3 May 1996 00:12:22 +0200 Received: (from j@localhost) by uriah.heep.sax.de (8.7.5/8.6.9) id AAA15521; Fri, 3 May 1996 00:07:03 +0200 (MET DST) From: J Wunsch Message-Id: <199605022207.AAA15521@uriah.heep.sax.de> Subject: Re: using DLT drive on FreeBSD To: freebsd-hackers@freebsd.org (FreeBSD hackers) Date: Fri, 3 May 1996 00:07:03 +0200 (MET DST) Cc: wilko@yedi.iaf.nl (Wilko Bulte) Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) In-Reply-To: <199605021801.UAA01622@yedi.iaf.nl> from Wilko Bulte at "May 2, 96 08:01:19 pm" X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E X-Mailer: ELM [version 2.4ME+ PL15 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk As Wilko Bulte wrote: > I think the 2.1R limit is 32kbytes. In the recent past there was a > discussion about this on this list (in relation to DAT drives??). 64 KB, this is enforced by physio(9) [man page not yet written :)]. Many SCSI adapters do only allow for 16 scatter/gather segments, and in the worst case, you need one of them for each physical page. (Well, i think that's what kept in my mind from the previous discussion.) Changing this will require a larger rework, or perhaps bounce buffers. ;) -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)