From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1hPQmd-0003Uf-6J for mharc-grub-devel@gnu.org; Sat, 11 May 2019 08:07:19 -0400 Received: from eggs.gnu.org ([209.51.188.92]:45405) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hPQmb-0003UV-F9 for grub-devel@gnu.org; Sat, 11 May 2019 08:07:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hPQmZ-0007Kc-Iw for grub-devel@gnu.org; Sat, 11 May 2019 08:07:17 -0400 Received: from mout.gmx.net ([212.227.17.22]:40463) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1hPQmW-0007GK-75 for grub-devel@gnu.org; Sat, 11 May 2019 08:07:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1557576423; bh=zy/RM1e+moRnyTg7+29Uf6/j2iIn4E+ZCfVVbJFtC0A=; h=X-UI-Sender-Class:Date:From:To:Subject:References:In-Reply-To; b=CwOvbOLQRnBPQpemK5y7kP8yu4DEjn5z94QaRpFeg9sk4L/nHA15Leg2/e4kYs3PS ZvzMhSjenOx1tuNUXGKn/sI5IlfIv1AgWoKazpV4tmuO5HGUH48skCb/jj+rgatlQp NtSFaNTvj5yg9QrKUIklI5t47doO5D826CbqCVAk= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from scdbackup.webframe.org ([79.222.46.132]) by mail.gmx.com (mrgmx105 [212.227.17.168]) with ESMTPSA (Nemesis) id 1M59GG-1hOKqh1Tdc-001BV3 for ; Sat, 11 May 2019 14:07:03 +0200 Date: Sat, 11 May 2019 14:05:25 +0200 From: "Thomas Schmitt" To: grub-devel@gnu.org Subject: Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition Content-Type: text/plain; charset="utf-8" References: <20190511105149.ju2q76l5dgpaajrj@pelzflorian.localdomain> In-Reply-To: <20190511105149.ju2q76l5dgpaajrj@pelzflorian.localdomain> Message-Id: <25430678662585939681@scdbackup.webframe.org> X-Provags-ID: V03:K1:AsXEJIJpdPg3Y78wTXTyA1G6RMDE1+ZW9tkeNRplvLwloh+Il0P Z3SRWp+FejZ5aNQPDQLdftUO5/agtXtopf5QFlb+YQArK7JCQM2WFfYQT97ZD5RyJ+0RJqF htXdZpSyWhOrt/QObr1RKuro+txN4YSXIsVDzBfzED8VtaANEyNqHg2fpM6hEX2n31WQxFL pO3TUvpzmwCyWC7kdEOHw== X-UI-Out-Filterresults: notjunk:1;V03:K0:YnJWXt3sswk=:u/2dNV1O6GacJSGzIaG9nN +XomtCkfGWP2fXDeDUti/uSzlcmRcb8zKm0tArX3F9wS1JcWgl0DoO0LzA6pN4QrQc9hMkafK Y32MLf4DYk+SUBG2lvzDxRvN9v/CwH/roJmCWkgNkDceckWPSBV9P7GsmN3WNMb2tvFAnzaUt T5dMym5Nwa1Kk0I2mdkwUICcUmLy4cJBKuKDv7eSqiezRIXGIZSCTztHtGzCLAPXP41lcGWey ARzA2/CJQUoA3BNInJ/Xgn4K/v0rm9KTAd4GTu9evRM6dYDNQFLrTRFvF8D3tbx3WuLQd0BpL 8690YRqn+cYVi+GISNLx2yUn7fYftniFa66UVIQhsUzmEIrDQZZwfEoaVIelFQO3K6BLS0Lkn kIt/EZwUvSwqSr8aHbcxhiyhn7S/5iiMQzZZQmF7MB0goiqA4dy86kb3I2wJguphKgGqlHobW wBZD2Pd2JFFK2M51LLJScwkR9pUP+Wbe8JDY0h8j4J9P4v+7WkU5MZkba9yMOTbqVT2hRuCJt 8a59UkxbOEQoOzQDuw7SZ0uS9+oE7Fh99k96OAPPsxs1e2zAL5bQPc7iNFhMmkI11RTWPnxnA oYeVQujukuERNfjANIiXAPyNLqUFJt/2IJUBSRODYbHsMZQFHGoEuXi50Bi3981SrfXLE4ZCk 4/KAnURrQj+IX/cv1i+i3xKtUEa7fZjpwWeQWDYor6djxRHFh1/lDce0byj8k5s0FwhlfDnjk 3NrDNkh1GsEHpNJViw8pUM+wXgeESRNNfbyMiqZsodC/3EWsbv2K05qJ9ua15+ZVUruOarG2r zu9kV9xZOjWgghuZOGTnYL6wjmT5YDXJflswUEA6ba3+VK5C2d/00wqcqmuoeuQIXpbg11x6H /4fIKKxcmU6CHltJD+BR8hRjRau1057559N4noOjDcwGP+bP1Ur54p/Xzrz7dKDwlslf+lBaC lSslKVQKmcw== X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 212.227.17.22 X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 11 May 2019 12:07:18 -0000 Hi, > The Windows 8.1 ISO image that I downloaded from Microsoft yesterday > also cannot be booted from a USB drive on neither this Macbook or > another computer. I wonder how other people can get to the impression that their attempts succeeded. (Will have to wait for somebody who is willing to go on with experiments after perceived success.) > I will continue testing the Windows 10 USB install medium: > /dev/sdb1 * 2048 15728639 15726592 7.5G c W95 FAT32 (LBA) That's not an EFI System Partition. So i assume the USB stick boots by BIOS and x86 machine code in the MBR. Unless we believe in EFI firmware that hops on arbitrary partitions ... > So I calculate 512*2048+454=1049030. > florian@florianmacbook ~$ sudo dd if=/dev/zero bs=1 count=16 seek=1049030 > of=/dev/sdb > It still boots. I believe what I calculated was wrong. You zeroized the LBA field but also the block count field. It should have been count=4 for the most minimal surgery (LBA=0x00000000). With count=16 you would have to seek to 512*2048+446 and afterwards would have to write a new partition table entry with LBA=0, non-zero block count, and probably a non-zero partition type. > I do not continue. Then let's disinfect our brains and go on with some useful work. :)) Have a nice day :) Thomas