gem5: update to d4b3e064adeeace3c3e7d106801f95c14637c12f

Mostly for --param to control debug properly.

Less README workarounds, more ./run automation, oh yeah.

README.adoc

@@ -8947,43 +8947,6 @@ When you want to break, just do a `Ctrl-C` on GDB shell, and then `continue`.
 
 And we now see the boot messages, and then get a shell. Now try the `/count.sh` procedure described for QEMU: <<gdb-step-debug-kernel-post-boot>>.
 
-==== gem5 wait for GDB to connect before running
-
-By default, gem5 does not wait for GDB to connect, which means that you might go past your point of interest.
-
-This can however be enabled with the `wait_for_remote_gdb` option:
-
-....
-patch -d "$(./getvar gem5_src_dir)" -p 1 < patches/manual/gem5-wait-gdb.patch
-....
-
-Just just proceed as usual:
-
-....
-./run --gem5
-....
-
-TODO why is this required, on another shell:
-
-....
-./gem5-shell
-....
-
-and finally:
-
-....
-./run-gdb --gem5 start_kernel
-....
-
-If I don't connect to the other shell on baremetal, the simulation breaks with:
-
-....
-....
-
-You have to remove the patch if you want to go back to running without waiting for GDB to connect.
-
-Bibliography: https://stackoverflow.com/questions/49296092/how-to-make-gem5-wait-for-gdb-to-connect-to-reliably-break-at-start-kernel-of-th
-
 ===== gem5 GDB step debug kernel aarch64
 
 TODO: GDB fails with:
@@ -10027,12 +9990,6 @@ Alternatively, skip directly to the C program main function with:
 ./run-gdb --arch arm --baremetal prompt main
 ....
 
-gem5 step debug requires a patch as mentioned at <<gem5-wait-for-gdb-to-connect-before-running>>:
-
-....
-patch -d "$(./getvar gem5_src_dir)" -p 1 < patches/manual/gem5-wait-gdb.patch
-....
-
 and then proceed as usual:
 
 ....

baremetal/arch/arm/no_bootloader/m5exit.S

@@ -0,0 +1,3 @@
+.global mystart
+mystart:
+    mov r0, #0; mov r1, #0; .inst 0xEE000110 | (0x21 << 16);

patches/manual/gem5-wait-gdb.patch

@@ -1,11 +0,0 @@
-diff --git a/configs/example/fs.py b/configs/example/fs.py
-index 3997ed76c..b4267ebc0 100644
---- a/configs/example/fs.py
-+++ b/configs/example/fs.py
-@@ -376,5 +376,6 @@ if buildEnv['TARGET_ISA'] == "arm" and options.generate_dtb:
-             sys = getattr(root, sysname)
-             sys.dtb_filename = create_dtb_for_system(sys, '%s.dtb' % sysname)
- 
-+test_sys.cpu[0].wait_for_remote_gdb = True
- Simulation.setWorkCountOptions(test_sys, options)
- Simulation.run(options, root, test_sys, FutureClass)

run

@@ -183,6 +183,9 @@ def main(args, extra_args=None):
         elif args.gem5_script == 'se':
             assert(args.exec_image is not None)
             cmd += [common.gem5_se_file, '-c', args.exec_image]
+        if args.debug_guest:
+            # https://stackoverflow.com/questions/49296092/how-to-make-gem5-wait-for-gdb-to-connect-to-reliably-break-at-start-kernel-of-th
+            cmd += ['--param', 'system.cpu[0].wait_for_remote_gdb = True']
     else:
         if not os.path.exists(common.image):
             raise_image_not_found()