From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lobo Subject: kernel addresses Date: Mon, 28 Oct 2002 13:22:20 -0800 (PST) Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20021028212220.80695.qmail@web80312.mail.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org Hello! I am an NT guy just getting into Linux stuff. Im going to be writing a SCSI initiator driver for an FC HBA. Had a couple of simple questions. 1) What exactly is the difference between Kernel logical and kernel virtual addresses? is the kernel logical address the address space of the kernel? Seems like kernel logical address have a constant offset from the physical address, and kernel virtual addresses dont. Its slightly confusing on why have these two separate terms at all? a kmalloced buffer gives a logical address, but a vmalloced gives a kernel virtual address. This kind of terminology confused me! 2) If a SCSI command is passed by a user level app, is there a buffer copy involved before it gets to the scsi initiator? I saw something about bounce buffers, but wasnt quite sure what it meant. So what are bounce buffers used for? Does the original buffer allocated by the user get mapped into a kernel virtual ( or logical???) address, locked down and passed down the stack? Any help is greatly appreciated. Thanks, Mark __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com