From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 2 Apr 2003 16:53:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 2 Apr 2003 16:53:04 -0500 Received: from neon-gw-l3.transmeta.com ([63.209.4.196]:31498 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id ; Wed, 2 Apr 2003 16:53:03 -0500 To: linux-kernel@vger.kernel.org From: "H. Peter Anvin" Subject: Re: 64-bit kdev_t - just for playing Date: 2 Apr 2003 14:03:58 -0800 Organization: Transmeta Corporation, Santa Clara CA Message-ID: References: <200303311541.50200.pbadari@us.ibm.com> <200304020931.38671.pbadari@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Disclaimer: Not speaking for Transmeta in any way, shape, or form. Copyright: Copyright 2003 H. Peter Anvin - All Rights Reserved Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Followup to: <200304020931.38671.pbadari@us.ibm.com> By author: Badari Pulavarty In newsgroup: linux.dev.kernel > > Roman, > > Here is the patch for sd to allow more than 256 disks. > There are few issues with the patch that need to be resolved. > > 1) With the patch I get 16 bits for minor. Since 4 bits are used for > partition, we get 12 bits to represent disks. So each major can support > 2^12 =3D 4096 disks. Disks 0 - 4095 are mapped to major=3D8,=20 > disks 4096 - 8191 to major =3D 65 and so on.. > > This means .. > > (i) I need to create nodes in /dev/ to match new for=20 > these disks. Currently "mknod" is broken due to glibc issues with dev_t. > > (ii) We need to worry about backward compatibility. For example: > 17th disk used to have <65, 0>. Now its major, minor is <8, 256>. > So /dev/ entires need to be re-created to match these, everytime > you reboot 2.4/2.5 etc. Greg KH udev might fix this for us.=20 > > 2) Do we still need 16 majors for disks ? > No, we don't. On the other hand, we really should change to 64 partitions/disk, same as for non-SCSI disks. 16 really is too small. -hpa -- at work, in private! "Unix gives you enough rope to shoot yourself in the foot." Architectures needed: ia64 m68k mips64 ppc ppc64 s390 s390x sh v850 x86-64