From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AB3C4C4332F for ; Wed, 9 Nov 2022 17:21:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=cBvPgdyJfCrQePlzuREFDQ9omfWhSPWpzB+7HrSDwZM=; b=ljCT4NM7vEnlVE EHF03AahnKTsA7qdS3jPUxg2slyRVfscxmvI49aL3TN8ohgVQc0251pB1ZiM6lL/l7758mgWuqWT4 bRKaRCGII9clcJEp69Rl9SS5fm/IlZgBILoPU0C3tLHsIPCgW3f7b/ksqG0V+zAXcNzFRbNlB0VCc v0MnI2XV3QSYZhp2l8THAAYolvTJyb6GM4/ttGmR39DwB3DznX+bFugwgcfcD397D7a5E6m5N5H4p IOZ7/+1ujQ/S3wTIabUW5CJn3vP1zYQ2k4tUIZ3QJnCjmCNSQWgkgCRh/5M/+axjHqGgwkVbQS9dN HZvPJfEWFb1VOHvTcTOw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1osol6-00FUfs-8n; Wed, 09 Nov 2022 17:21:04 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1osol4-00FUfN-UF for linux-mtd@bombadil.infradead.org; Wed, 09 Nov 2022 17:21:02 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=U8E7Jm8e1876qUqey5/8BiJLc1XaDBvWcjC7yx9ROzg=; b=gmH5h/mQ6qEquszdoCqVrpILhD iK+Kn9JHkuehJ2b1rL/vezAXYWk0g3pgHr7Iy/bU1gc3he4FIVq3yXOY55t5UfEjBxHetnvUf7TEN sA7IMRXPsK/N42x13tITnCCN/virflVFzUjbq/NWOF+5NR7/TJJCqt76qufO0ugPmwCpdfJJivc5a osQkbkyKeXSgy0E4O0x9ZfTPlAFK/2N170Qq7YhrJqYEP+1KaiC2loLtcK8AdIBu3jn/6awOQon6Z jv7RxpJFjzlqVSJ4ty0ykIzFEYXt2wMLx5Hh5VwgxdpsOcaf/3h9HS4qDfKuj4uHxAEnu4qohzwjs 2sB3e4pQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1osol3-00BLdJ-H0; Wed, 09 Nov 2022 17:21:01 +0000 Date: Wed, 9 Nov 2022 17:21:01 +0000 From: Matthew Wilcox To: Daniel Golle Cc: Jens Axboe , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Davidlohr Bueso , "Martin K. Petersen" , Chaitanya Kulkarni , Ming Lei , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-efi@vger.kernel.org Subject: Re: [PATCH v4 2/5] block: add partition parser for U-Boot uImage.FIT Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Wed, Nov 09, 2022 at 02:36:11PM +0000, Daniel Golle wrote: > On Wed, Nov 09, 2022 at 01:58:29PM +0000, Matthew Wilcox wrote: > > ... actually, why can't you call read_part_sector() and avoid all of > > this? > > I've tried that before and the problem is that read_part_sector() > returns a pointer to one sector (typically 512 bytes) of data. > And this pointer should not be accesses beyond sector boundaries, > right? You'd have to call read_part_sector() again for the next > sector. > > The FIT structure, however, usually exceeds the size of one sector, > and having a continous memory area covering the structure as a whole > is crucial for libfdt to do its job. > > I could, of course, use read_part_sector() to copy all sectors > covering the FIT structure into a buffer, but that seemed strange > given that read_part_sector() actually used read_mapping_page() > (and now uses read_mapping_folio()) internally and then returns a > pointer to the offset within the page/folio. So why not read it in one > piece in first place instead of having it first split up to sectors > by read_part_sector() just to then having to reassemble it into a > continous buffer again. Are you guaranteed that it's "sufficiently" aligned on storage so that it fits entirely within a single page? If not, you'll have to copy it, vmap it, or fix libfdt to handle a segmented buffer. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/