Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262955AbUJ1VHv (ORCPT ); Thu, 28 Oct 2004 17:07:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263115AbUJ1VHs (ORCPT ); Thu, 28 Oct 2004 17:07:48 -0400 Received: from [129.105.5.125] ([129.105.5.125]:25751 "EHLO delta.ece.northwestern.edu") by vger.kernel.org with ESMTP id S262955AbUJ1VDJ (ORCPT ); Thu, 28 Oct 2004 17:03:09 -0400 Message-ID: <41815EED.9070202@ece.northwestern.edu> Date: Thu, 28 Oct 2004 16:04:45 -0500 From: Lei Yang User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4.2) Gecko/20040921 X-Accept-Language: en-us, en MIME-Version: 1.0 To: "\"Shesha B. \" Sreenivasamurthy" Cc: LinuxKernel Group , kernelnewbies Subject: Re: set blksize of block device References: <417FE6A8.5090803@ece.northwestern.edu> <417FE937.1040304@ece.northwestern.edu> <41804F04.4000300@ece.northwestern.edu> <1098981325.3279.5.camel@arcane> In-Reply-To: <1098981325.3279.5.camel@arcane> X-Enigmail-Version: 0.76.8.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2122 Lines: 73 Shesha B. Sreenivasamurthy wrote: >Firstly you cannot set the block size to lesser than 512. > >When there is a request for the IO, you populate "struct req" data >structure which you will pass it to the kernel or lower level SCSI/SATA >driver. In the "struct req" there is a field "b_size" which may be what >you are interested in. At the user level you can use the IOCTLs to set >the block size of the RAW block device. > >-Shesha > > I understand that for real block device (like hard disk), block size cannot be less than 512. But to ramdisks, I think they are truely random addressable, and should be able to move on blocks even with size of 2 bytes. Any comments? >On Wed, 2004-10-27 at 18:44, Lei Yang wrote: > > >>If nobody could answer this question, what about another one? Is there a >>system call or a kernel interface that would allow me to write a block >>of data to block 1 of a certain block device? >> >>Thanks for your reply in advance! >> >>Lei >> >>Lei Yang wrote: >> >> >> >>>Please cc me if you have answers to this, I am not on the list. Thanks >>>a lot! >>> >>>Lei Yang wrote: >>> >>> >>> >>>>Hello, >>>> >>>>I am learning block device drivers and have a newbie question. Given >>>>a block device, is there anyway that I could set its block size? For >>>>example, I want to write a block device driver that will work on an >>>>existing block device. In this driver, I want block size smaller. >>>>(The idea looks confusing but I could explain if anybody is >>>>interested :- ) However, typically the block size is 1KB, now I >>>>want to set it to 512 or 256. Can I do it? >>>> >>>>TIA >>>>Lei >>>> >>>> >>>> >>> >>> >>> >> >>-- >>Kernelnewbies: Help each other learn about the Linux kernel. >>Archive: http://mail.nl.linux.org/kernelnewbies/ >>FAQ: http://kernelnewbies.org/faq/ >> >> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/