gem5: allow prof and perf builds, and comment on them

README.adoc

@@ -12167,6 +12167,15 @@ Benchmarks present at:
 
 * xref:benchmark-emulators-on-userland-executables[xrefstyle=full]
 
+==== gem5 prof and perf builds
+
+Profiling builds as of 3cea7d9ce49bda49c50e756339ff1287fd55df77 both use: `-g -O3` and disable asserts and logging like the <<gem5-fast-build>> and:
+
+* `prof` uses `-pg` for gprof
+* `perf` uses `-lprofile` for google-pprof
+
+See also: <<profiling-userland-programs>>.
+
 ==== gem5 clang build
 
 TODO test properly, benchmark vs GCC.

common.py

@@ -151,7 +151,7 @@ consts['build_type_choices'] = [
     'debug'
 ]
 consts['gem5_build_type_choices'] = consts['build_type_choices'] + [
-    'fast',
+    'fast', 'prof', 'perf',
 ]
 consts['build_type_default'] = 'opt'
 # Files whose basename start with this are gitignored.