Merge branch 'improved-mmio' into 'master'

Allow Mmio to work with const fn

See merge request !43
3 jobs for master in 1 minute (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Build
passed #24998
build:linux

00:00:18

passed #24999
build:redox

00:00:18

 
  Test
failed #25000
test:redox

00:00:41

 
Name Stage Failure
failed
test:redox Test
redoxfs: mounted filesystem on /tmp/.tmpmEPqaJ/redoxer.bin to /tmp/.tmpmEPqaJ/redoxer
redoxer: replacing '/builds/redox-os/syscall/target/x86_64-unknown-redox/debug/deps/syscall-28222d485c747e4c' with '/root/target/x86_64-unknown-redox/debug/deps/syscall-28222d485c747e4c' in arguments
redoxer: copying '.' to '/root'
qemu-system-x86_64: cannot set up guest memory 'pc.ram': Cannot allocate memory

## redoxer (failure, qemu exit status ExitStatus(ExitStatus(256)) ##
error: test failed, to rerun pass '--lib'
redoxer cargo: exit code: 2
ERROR: Job failed: exit code 1