Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757250Ab0HCRSF (ORCPT ); Tue, 3 Aug 2010 13:18:05 -0400 Received: from mail-px0-f174.google.com ([209.85.212.174]:44431 "EHLO mail-px0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757212Ab0HCRSD convert rfc822-to-8bit (ORCPT ); Tue, 3 Aug 2010 13:18:03 -0400 MIME-Version: 1.0 In-Reply-To: <4C583EE6.4030203@kernel.org> References: <1280776623-1337-1-git-send-email-wad@chromium.org> <4C583EE6.4030203@kernel.org> From: Kay Sievers Date: Tue, 3 Aug 2010 19:17:15 +0200 Message-ID: Subject: Re: [PATCH RFC] efi: add and expose efi_partition_by_guid To: Tejun Heo Cc: Will Drewry , linux-kernel@vger.kernel.org, Jens Axboe , Karel Zak , "David S. Miller" , Andrew Morton , Joe Perches Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2018 Lines: 49 On Tue, Aug 3, 2010 at 18:08, Tejun Heo wrote: > On 08/02/2010 09:17 PM, Will Drewry wrote: >> EFI's GPT partitioning scheme expects that all partitions have a unique >> identifiers.  After initial partition scanning, this information is >> completely lost to the rest of the kernel. >> >> efi_partition_by_guid exposes GPT parsing support in a limited fashion >> to allow other portions of the kernel to map a partition from GUID to >> map. > Kay, you were talking about using GUID in GPT for finding out root > device and so on. Does this fit your use case too? If not it would > be nice to find out something which can be shared. Yeah, we have something similar in mind since a while, to be able to safely boot a box without an initramfs, and to be able to to specify something like: root=PARTUUID=6547567-575-7567-567567-57 root=PARTLABEL=foo on the kernel commandline. The current 'blkid' already reports stuff like, to have the same information in userspace: $ blkid -p -oudev /dev/sde1 ID_FS_LABEL=10GB ID_FS_LABEL_ENC=10GB ID_FS_UUID=5aafa1bb-70a7-4fe6-b93f-30658ec99fac ID_FS_UUID_ENC=5aafa1bb-70a7-4fe6-b93f-30658ec99fac ID_FS_VERSION=1.0 ID_FS_TYPE=ext4 ID_FS_USAGE=filesystem ID_PART_ENTRY_SCHEME=gpt ID_PART_ENTRY_UUID=1f765dcb-5214-bd47-b1c5-f2f18848335e ID_PART_ENTRY_TYPE=a2a0d0eb-e5b9-3344-87c0-68b6b72699c7 ID_PART_ENTRY_NUMBER=1 I guess we want to store these identifiers directly into the partition structure, independent of the partition format, so any code can register a callback for a new block device, and can just check if that's the device in question. Walking the block devices would just be something usual provided by the driver core, instead of having some specific EFI walk functions. Kay -- 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/