reject non-x86 targets
reject non-x86 targets

for now, of course (until someone writes support for them ...)

ujamjar/rumpuser-baremetal,rumpkernel-attic/rumprun-baremetal,rumpkernel-attic/rumprun-baremetal,rumpkernel-attic/rumprun-baremetal,ujamjar/rumpuser-baremetal,ujamjar/rumpuser-baremetal