From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1jcph7-0007pU-UV for mharc-grub-devel@gnu.org; Sun, 24 May 2020 08:25:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35350) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jcph0-0007jV-8c for grub-devel@gnu.org; Sun, 24 May 2020 08:25:26 -0400 Received: from ionic.de ([87.98.244.45]:48807 helo=mail.ionic.de) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jcpgz-0004kZ-GS for grub-devel@gnu.org; Sun, 24 May 2020 08:25:25 -0400 Received: from apgunner.local.home.ionic.de (home.ionic.de [217.92.117.31]) by mail.ionic.de (Postfix) with ESMTPSA id C2F694F0BA17 for ; Sun, 24 May 2020 12:25:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=ionic.de; s=default; t=1590323122; bh=lvkM+CRvh3gVHpk1DG3K0c3SNz3633ksvBx1UaATd4o=; h=From:To:Subject:Date:In-Reply-To:References:From; b=edDHtF7Giqczh3yrHSrnbV69PHCxbrWj5Dxd/i4kfov1os+Xuye9E6U6gdUMBjard NklDywXKsTIHtq1FDdosFS3J5jECykJuJC6GpQotm+GZzvQYwHHC+Bnjj+MKhgWP5n At9eMKYuSg9dde2TtFZoeMDBl+rUxXmtfnGQeHGY= From: Mihai Moldovan To: The development of GNU GRUB Subject: [PATCH v2 5/7] docs/grub: document --emu-512b install option Date: Sun, 24 May 2020 14:25:15 +0200 Message-Id: <20200524122517.5010-6-ionic@ionic.de> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200524122517.5010-1-ionic@ionic.de> References: <20200524122517.5010-1-ionic@ionic.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=87.98.244.45; envelope-from=ionic@ionic.de; helo=mail.ionic.de X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/24 07:43:16 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 24 May 2020 12:25:26 -0000 --- docs/grub.texi | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/docs/grub.texi b/docs/grub.texi index 1ce9993a5..f071487d6 100644 --- a/docs/grub.texi +++ b/docs/grub.texi @@ -6433,6 +6433,21 @@ validate the contents of the bootloader embedding area, or in more modern systems with GPT-style partition tables (@pxref{BIOS installation}) where GRUB does not reside in any unpartitioned space outside of the MBR. Disable the Reed-Solomon codes with this option. + +@item --emu-512b +By default on x86 BIOS systems, @command{grub-install} assumes a 512 +bytes sector size when generating and writing the core image. This +option makes grub use the disk's native sector size for addressing the +core image's blocks and a 512 bytes read block size, as often found +with old/buggy system firmware. To that effect, the core image is +spread out so that each read block starts on a proper hardware sector. +Additionally, it enables read block and sector size autodetection in +the @samp{biosdisk} access module by setting the +@samp{biosdisk_autodetect_sector_size} variable to @samp{1}. You should +@emph{only} use this option if you @emph{know} that your system +firmware is buggy and can't handle disks with sector sizes bigger than +512 bytes correctly and your machine is trying to boot off such a disk. +It @emph{will} otherwise break normal operation. @end table @node Invoking grub-mkconfig -- 2.25.1