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 X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 99F36C433FE for ; Wed, 22 Sep 2021 11:52:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C67F6113E for ; Wed, 22 Sep 2021 11:52:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235833AbhIVLyG (ORCPT ); Wed, 22 Sep 2021 07:54:06 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:50806 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235802AbhIVLyF (ORCPT ); Wed, 22 Sep 2021 07:54:05 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 16BE4201F0; Wed, 22 Sep 2021 11:52:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1632311555; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lKYO+Tpc8e3f34No4zgqOS6u8nCy/Ay6+o3tevL0n78=; b=ktKvNvwDsM5ECFgPdsFxp49D78fW9ZPLENfrY+04gVtbFHFRtdEq6UHpLkQXBSZuS1Bofw bQr5k5dMgevjBqnPAnFe+G6J6PleWrrQ1YHJLX1J+Jz6QGQ6LxzOGoc9DZXf6y7E3N+WBp 4PC/wPF5D9ChSCqmGWVYenDgumqySeM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1632311555; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lKYO+Tpc8e3f34No4zgqOS6u8nCy/Ay6+o3tevL0n78=; b=RPzt5dLGLXhUFMZAzp1esSCE3B5Strt4tPRv/jAq/IocLvd2VrFTlWCcFBQbsJI2sgZohE RcgAcQ6vIFXH0VBA== Received: from echidna.suse.de (ddiss.udp.ovpn2.nue.suse.de [10.163.47.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id E00CDA3BA9; Wed, 22 Sep 2021 11:52:34 +0000 (UTC) From: David Disseldorp To: linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org Cc: viro@zeniv.linux.org.uk, willy@infradead.org, David Disseldorp Subject: [PATCH v2 3/5] docs: remove mention of "crc" cpio format support Date: Wed, 22 Sep 2021 13:52:20 +0200 Message-Id: <20210922115222.8987-3-ddiss@suse.de> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210922115222.8987-1-ddiss@suse.de> References: <20210922115222.8987-1-ddiss@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org init/initramfs.c only supports extraction of cpio archives carrying the "newc" header magic ("070701"). Remove statements indicating support for the "crc" cpio format. Signed-off-by: David Disseldorp --- .../early-userspace/buffer-format.rst | 24 +++++++------------ 1 file changed, 8 insertions(+), 16 deletions(-) Version 2: - reword initramfs padding description, as suggested by Matthew Wilcox diff --git a/Documentation/driver-api/early-userspace/buffer-format.rst b/Documentation/driver-api/early-userspace/buffer-format.rst index 7f74e301fdf3..0df76bca444c 100644 --- a/Documentation/driver-api/early-userspace/buffer-format.rst +++ b/Documentation/driver-api/early-userspace/buffer-format.rst @@ -14,10 +14,10 @@ is different. The initramfs buffer contains an archive which is expanded into a ramfs filesystem; this document details the format of the initramfs buffer format. -The initramfs buffer format is based around the "newc" or "crc" CPIO -formats, and can be created with the cpio(1) utility. The cpio -archive can be compressed using gzip(1). One valid version of an -initramfs buffer is thus a single .cpio.gz file. +The initramfs buffer format is based around the "newc" CPIO format, and +can be created with the cpio(1) utility. The cpio archive can be +compressed using gzip(1). One valid version of an initramfs buffer is +thus a single .cpio.gz file. The full format of the initramfs buffer is defined by the following grammar, where:: @@ -40,9 +40,8 @@ grammar, where:: In human terms, the initramfs buffer contains a collection of -compressed and/or uncompressed cpio archives (in the "newc" or "crc" -formats); arbitrary amounts zero bytes (for padding) can be added -between members. +compressed and/or uncompressed cpio archives (in the "newc" format), +with arbitrary amount of zero-byte padding between members. The cpio "TRAILER!!!" entry (cpio end-of-archive) is optional, but is not ignored; see "handling of hard links" below. @@ -55,7 +54,7 @@ by the ASCII string "000012ac"): ============= ================== ============================================== Field name Field size Meaning ============= ================== ============================================== -c_magic 6 bytes The string "070701" or "070702" +c_magic 6 bytes The string "070701" c_ino 8 bytes File inode number c_mode 8 bytes File mode and permissions c_uid 8 bytes File uid @@ -68,8 +67,7 @@ c_min 8 bytes Minor part of file device number c_rmaj 8 bytes Major part of device node reference c_rmin 8 bytes Minor part of device node reference c_namesize 8 bytes Length of filename, including final \0 -c_chksum 8 bytes Checksum of data field if c_magic is 070702; - otherwise zero +c_chksum 8 bytes Ignored; reserved for unsupported "crc" format ============= ================== ============================================== The c_mode field matches the contents of st_mode returned by stat(2) @@ -78,12 +76,6 @@ on Linux, and encodes the file type and file permissions. The c_filesize should be zero for any file which is not a regular file or symlink. -The c_chksum field contains a simple 32-bit unsigned sum of all the -bytes in the data field. cpio(1) refers to this as "crc", which is -clearly incorrect (a cyclic redundancy check is a different and -significantly stronger integrity check), however, this is the -algorithm used. - If the filename is "TRAILER!!!" this is actually an end-of-archive marker; the c_filesize for an end-of-archive marker must be zero. -- 2.31.1