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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 DA83BC433E0 for ; Fri, 15 Jan 2021 16:12:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95A5F238EB for ; Fri, 15 Jan 2021 16:12:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727253AbhAOQMW (ORCPT ); Fri, 15 Jan 2021 11:12:22 -0500 Received: from drop1.michaelkloos.com ([67.205.190.89]:37832 "EHLO drop1.michaelkloos.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726669AbhAOQMW (ORCPT ); Fri, 15 Jan 2021 11:12:22 -0500 X-Greylist: delayed 565 seconds by postgrey-1.27 at vger.kernel.org; Fri, 15 Jan 2021 11:12:21 EST Received: from qpc.home.michaelkloos.com (cpe-173-88-115-50.columbus.res.rr.com [173.88.115.50]) by drop1.michaelkloos.com (Postfix) with ESMTPSA id 5DB2C410DC for ; Fri, 15 Jan 2021 16:01:46 +0000 (UTC) To: util-linux@vger.kernel.org From: "Michael T. Kloos" Subject: FAT12 format does not honor the -R option Message-ID: Date: Fri, 15 Jan 2021 11:01:45 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: util-linux@vger.kernel.org "mkfs.vfat -F 12 -R 2 /dev/loop0" does not seem to honor the -R option.  It just defaults to 0x20 for the reserved sector count. I can hexedit the FS to move the file allocation table contents and change 0x20 to 0x02 in the reserved sector count field. Mounting this seems to work fine under the Linux FAT driver from my limited experimentation.  It just seems like a waste of space reserving that many sectors in a FAT12 FS where it is most likely to be used in space constrained applications.  Is this a bug or is it working around some compatibility issue with 2 reserved pages? Thanks, ----Michael