get rid of machine2, that was too insane

README.adoc

@@ -16582,6 +16582,10 @@ Version 2.0 (GICv2) is only described in terms of the GICv3 optional support for
 
 The specific models have names of type GIC-600, GIC-500, etc.
 
+In QEMU v4.0.0, the GICv3 can be selected with an extra `-machine gic_version=3` option.
+
+In gem5 3126e84db773f64e46b1d02a9a27892bf6612d30, the GIC is determined by selecting the platform as explained at: <<gem5-arm-platforms>>.
+
 ==== ARM paging
 
 TODO create a minimal working aarch64 example analogous to the x86 one at: https://github.com/cirosantilli/x86-bare-metal-examples/blob/6dc9a73830fc05358d8d66128f740ef9906f7677/paging.S

common.py

@@ -719,16 +719,6 @@ Incompatible archs are skipped.
             else:
                 if not env['_args_given']['machine']:
                     env['machine'] = 'virt'
-                    if env['arch'] == 'arm':
-                        # highmem=off needed since v3.0.0 due to:
-                        # http://lists.nongnu.org/archive/html/qemu-discuss/2018-08/msg00034.html
-                        env['machine2'] = 'highmem=off'
-                    elif env['arch'] == 'aarch64':
-                        # TODO allow the Gic version to be controlled from the CLI.
-                        # env['machine2'] = 'gic_version=3'
-                        env['machine2'] = None
-        else:
-            env['machine2'] = None
 
         # Buildroot
         env['buildroot_build_dir'] = join(env['buildroot_out_dir'], 'build', env['buildroot_build_id'], env['arch'])

run

@@ -636,19 +636,19 @@ Extra options to append at the end of the emulator command line.
                                 .format(virtfs_dir=virtfs_dir, virtfs_tag=virtfs_tag),
                             LF,
                         ])
-                if self.env['machine2'] is not None:
+                machines = [self.env['machine']]
-                    # Multiple -machine options can also be given comma separated in one -machine.
+                if self.env['arch'] == 'arm':
-                    # We use multiple because the machine is used as an identifier on baremetal tests
+                    # Needed since v3.0.0 due to:
-                    # build paths, so better keep them clean.
+                    # http://lists.nongnu.org/archive/html/qemu-discuss/2018-08/msg00034.html
-                    machine2 = ['-machine', self.env['machine2'], LF]
+                    machines.append('highmem=off')
-                else:
+                machines_cli = []
-                    machine2 = []
+                for machine in machines:
+                    machines_cli.extend(['-machine', machine, LF])
                 cmd.extend(
                     [
                         self.env['qemu_executable'], LF,
-                        '-machine', self.env['machine'], LF,
                     ] +
-                    machine2 +
+                    machines_cli +
                     [
                         '-device', 'rtl8139,netdev=net0', LF,
                         '-gdb', 'tcp::{}'.format(self.env['gdb_port']), LF,