The problem: a Linux user on a legacy/BIOS system would like to install Windows 10 alongside Linux (on real hardware, not in a VM). Assume preparation issues such as partitioning hard drives to create space for Windows are already resolved. Also assume that no CD/DVD drive is available. How does one, using only utilities available under Linux, go about creating the Windows 10 installation media?
A Windows 10 iso can be downloaded from Microsoft, which looks like a good start. I presume the easiest way of doing something with that iso under the circumstances described would be to dd it to a USB drive:
dd if=/path/to/Win10.iso of=/path/to/USB/drive/ I have not yet tried that but think it likely to work as advertised. But are there other alternatives?
For example this page https://ckirbach.wordpress.com/2016/10/24/how-to-create-a-windows-10-usb-installation-media-on-linux/ indicates that mounting the iso image and copying its contents to an NTFS-formatted USB drive, one that has already been made bootable using syslinux, will also work. However, despite the fact that I have recently created a few syslinux-bootable USB drives and understand well how to do this, the process described there does not work for me. And it's not because the USB drive is not bootable: rather, it seems to me it doesn't work because syslinux can't find something bootable among the files copied over from the loop-mounted Windows 10 iso (that page doesn't go into what seems to me a ciritical step--creation of a syslinux configuration file).
It might also be possible, using syslinux's memdisk, to boot the Windows 10 iso from a USB drive. Just make the drive bootable using syslinux, copy the iso over to it, and create an appropriate syslinux.cfg that lists the iso as a boot item. Something like:
APPEND iso raw
I've tried that as well but am also not meeting with success ("bad file number"). I suppose this might be the method least likely to succeed since I know, based on past experience, that some iso's simply are not bootable via memdisk.
Input on accomplishing this task will be appreciated.
PS I don't have access to any installed Windows environments, so descriptions of ways to accomplish this task that involve Windows utilities are not being solicited.