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 _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
