From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Anderson Subject: Re: request_buffer versus buffer in Scsi_Cmnd Date: Fri, 27 Sep 2002 09:29:38 -0700 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20020927162938.GA1366@beaverton.ibm.com> References: <200209270915.CAA96467@classic.engr.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <200209270915.CAA96467@classic.engr.sgi.com> List-Id: linux-scsi@vger.kernel.org To: Jeremy Higdon Cc: linux-scsi@vger.kernel.org Jeremy Higdon [jeremy@classic.engr.sgi.com] wrote: > I notice that the qlogicfc driver calls pci_map_sg with the request_buffer > field and pci_unmap_sg with the buffer field. > > >From looking at the code in drivers/scsi/scsi*, it would appear that they > are mostly the same, and the fact that qlogicfc works would seem to confirm > that. However, the fact that there are two different fields leads me > to ask what the difference is supposed to be. > There are a few fields in the Scsi_Cmnd that are duplicated to contain the original values that the scsi cmd was submitted with mostly for retry. Some Pairs: request_buffer, buffer request_bufflen, bufflen use_sg, old_use_sg etc. a few more are listed in the scsi_retry_command. -andmike -- Michael Anderson andmike@us.ibm.com