Installing openwrt on x86-64 - Riseup
https://we.riseup.net/wikis/193527Most openwrt installs are on small embedded routers and you are working with a build for that particular router type that already includes the right kernel modules, knows about the flash size and layout, etc. But it’s also possible to install on normal x86 PC hardware, and the openwrt project provides builds for both x86 32bit and 64bit hardware.
Installing openwrt on x86-64 - Riseup
we.riseup.net › wikis › 193527Create your own partitions and filesystems of larger sizes, then untar the openwrt-x86-64-rootfs.tar.gz tarball in the root partition and put the openwrt-x86-64-vmlinuz kernel in the /boot parition and then install and configure the bootloader to point at the kernel and new partition as root.