Rename and add features

Author: remimimimimi

Cargo.toml

@@ -9,12 +9,15 @@ edition = "2018"
 
 [dependencies]
 bitflags = "1.1.0"
-x86_64 = { version = "0.14.0", default-features = false, features = ["instructions"] }
+x86_64 = { version = "0.14.0", default-features = false, features = ["instructions"], optional = true }
 
 [features]
-default = [ "nightly" ]
-stable = [ "x86_64/external_asm" ]
-nightly = [ "x86_64/inline_asm" ]
+default = [ "port_nightly"]
+#default = [ "port", "nightly" ]
+port_stable = [ "x86_64/external_asm" ]
+port_nightly = [ "x86_64/inline_asm" ]
+mmio_stable = []
+mmio_nightly = []
 
 [package.metadata.release]
 no-dev-version = true