diff --git a/README.adoc b/README.adoc
index a269433..fd8a7a4 100644
--- a/README.adoc
+++ b/README.adoc
@@ -353,13 +353,24 @@ To get a terminal, either open a new shell and run:
 ./gem5-shell
 ....
 
-or if you are inside tmux, which I highly recommend, just run gem5 with:
+The only way to exit the shell is to kill the gem5 on the previous shell
+
+If you are inside tmux, which I highly recommend, just run gem5 with:
 
 ....
 ./run --gem5 --tmux
 ....
 
-This will open up a split terminal by default so that you can see both the gem5 stdout and the terminal. See also: <<tmux-gem5>>
+This will open up a split terminal by default so that you can see both the gem5 stdout and the terminal. See also: <<tmux-gem5>>.
+
+At the end of boot, it might not be very clear that you have the shell since some <<printk>> messages may appear in front of the prompt like this:
+
+....
+# <6>[    1.215329] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x1cd486fa865, max_idle_ns: 440795259574 ns
+<6>[    1.215351] clocksource: Switched to clocksource tsc
+....
+
+but if you look closely, the `PS1` prompt marker `#` is there already, just hit enter and a clear prompt line will appear.
 
 If you forgot to open the shell and gem5 exit, you can inspect the terminal output post-mortem at:
 
diff --git a/build-gem5 b/build-gem5
index 48228ac..19b8fcc 100755
--- a/build-gem5
+++ b/build-gem5
@@ -6,6 +6,7 @@ import os
 import pathlib
 import shutil
 import subprocess
+import time
 
 import common
 
@@ -23,6 +24,7 @@ disks_dir = os.path.join(common.gem5_system_dir, 'disks')
 if args.clean:
     common.rmrf(common.gem5_build_dir)
 else:
+    start_time = time.time()
     os.makedirs(binaries_dir, exist_ok=True)
     os.makedirs(disks_dir, exist_ok=True)
     if  not os.path.exists(os.path.join(common.gem5_src_dir, '.git')):
@@ -81,3 +83,5 @@ else:
     term_src_dir = os.path.join(common.gem5_src_dir, 'util/term')
     subprocess.check_call(['make', '-C', term_src_dir])
     shutil.copy2(os.path.join(term_src_dir, 'm5term'), common.gem5_m5term)
+    end_time = time.time()
+    common.print_time(end_time - start_time)
diff --git a/build-qemu b/build-qemu
index 554d8bf..ad9e5c0 100755
--- a/build-qemu
+++ b/build-qemu
@@ -3,6 +3,7 @@
 import multiprocessing
 import os
 import subprocess
+import time
 
 import common
 
@@ -18,6 +19,7 @@ args = common.setup(parser)
 if args.clean:
     common.rmrf(common.qemu_build_dir)
 else:
+    start_time = time.time()
     os.makedirs(common.qemu_build_dir, exist_ok=True)
     subprocess.check_call(
         [
@@ -37,5 +39,8 @@ else:
             # TODO factor with build.
             '-j', str(multiprocessing.cpu_count()),
         ],
-        cwd=common.qemu_build_dir
+        cwd=common.qemu_build_dir,
+        extra_env={'PATH': '/usr/lib/ccache:' + os.environ['PATH']},
     )
+    end_time = time.time()
+    common.print_time(end_time - start_time)
diff --git a/run b/run
index eb7796a..8f3ad7b 100755
--- a/run
+++ b/run
@@ -1,10 +1,11 @@
 #!/usr/bin/env python3
 
 import os
+import re
 import shlex
 import subprocess
 import sys
-import re
+import time
 
 import common
 
@@ -463,4 +464,8 @@ Run QEMU with VNC instead of the default SDL. Connect to it with:
 if __name__ == '__main__':
     parser = get_argparse()
     args = common.setup(parser)
-    sys.exit(main(args))
+    start_time = time.time()
+    exit_status = main(args)
+    end_time = time.time()
+    common.print_time(end_time - start_time)
+    sys.exit(exit_status)