gem5 CPU types

README.adoc

@@ -12186,7 +12186,16 @@ gem5 has a few in tree CPU models for different purposes.
 
 In fs.py and se.py, those are selectable with the `--cpu-type` option.
 
-The information to make accurate models isn't generally public for non-free CPUs, so either you must either rely vendor provided models or on experiments/reverse engineering.
+The information to make highly accurate models isn't generally public for non-free CPUs, so either you must either rely vendor provided models or on experiments/reverse engineering.
+
+There is no simple answer for "what is the best CPU", in theory you have to understand each model and decide which one is closer your target system.
+
+Whenever possible, stick to:
+
+* vendor provide ones obviously, e.g. ARM Holdings models of ARM cores, unless there is good reason not to, as they are the most likely to be accurate
+* newer models instead of older models
+
+Both of those can be checked with `git log` and `git blame`.
 
 ==== List gem5 CPU types
 
@@ -12246,6 +12255,11 @@ ex5 LITTLE core (based on the ARM Cortex-A7)
 ____
 +
 Implemented by Pierre-Yves Péneau from LIRMM, which is a research lab in Montpellier, France, in 2017.
+* `O3_ARM_v7a`: implemented by Ronald Dreslinski from the https://en.wikipedia.org/wiki/University_of_Michigan[University of Michigan] in 2012
++
+Not sure why it has v7a in the name, since I believe the CPUs are just the microarchitectural implementation of any ISA, and the v8 hello world did run.
++
+The CLI option is named slightly differently as: `--cpu-type O3_ARM_v7a_3`.
 
 ===== gem5 DeriveO3CPU