[mkroot] x86_64 x32 mkroot port status report

[Alain Toussaint]

Hello,

Just reporting that I successfully built and booted up in both qemu and
real hardware an x32[1] ABI port of mkroot along with musl-cross-make.

[1] == not to be confused with a 32 bit i686 userspace; the
particularity are 4 bytes pointers like i686 but there is full access
to the 15 integer registers and 16 floating points registers like
x86_64.

On real hardware, it is necessary to pass the command
init=/usr/bin/busybox sh (or /bin/busybox sh) to the bootloader but
otherwise, there are no other requirements.

The dropbear package does not compile and finally, I was able to
install gcc 6.3.0 from mcm in native x32 configuration and it run.

Alain