common: one char arch shorthands, fail nicely on invalid arch

README.adoc

@@ -1630,7 +1630,7 @@ which automatically finds unstripped shared libraries on the host for us.
 
 See also: https://stackoverflow.com/questions/8611194/debugging-shared-libraries-with-gdbserver/45252113#45252113
 
-== Architectures
+== CPU architecture
 
 The portability of the kernel and toolchains is amazing: change an option and most things magically work on completely different hardware.
 
@@ -1649,6 +1649,19 @@ Debug:
 ./rungdb -a arm
 ....
 
+We also have one letter shorthand names for the architectures:
+
+....
+# aarch64
+./run -a A
+# arm
+./run -a a
+# mips64
+./run -a m
+# x86_64
+./run -a x
+....
+
 Known quirks of the supported architectures are documented in this section.
 
 === mips64

common

@@ -22,6 +22,24 @@ common_bench_cmd() (
 set_common_vars() {
   arch="$1"
   gem5="${2:-false}"
+  case "$arch" in
+    a|arm)
+      arch=arm
+      ;;
+    A|aarch64)
+      arch=aarch64
+      ;;
+    m|mips64)
+      arch=mips64
+      ;;
+    x|x86_64)
+      arch=x86_64
+      ;;
+    *)
+      printf "unknown arch: ${arch}\n" 1>&2
+      exit 2
+      ;;
+  esac
   common_suffix="${3:-}"
   buildroot_dir="${root_dir}/buildroot"
   arch_dir="$arch"