Update docs and tests for ARM gdb support

Updated docs to now show arm is supported.
Updated the build test to run on aarch

Signed-off-by: Jack Thomson <[email protected]>

docs/gdb-debugging.md

@@ -1,14 +1,16 @@
 # GDB Debugging with Firecracker
 
+**The GDB feature is not for production use.**
+
 Firecracker supports debugging the guest kernel via GDB remote serial protocol.
 This allows us to connect GDB to the firecracker process and step through debug
-the guest kernel. Currently only debugging on x86 is supported.
+the guest kernel.
 
 The GDB feature requires Firecracker to be booted with a config file.
 
 ## Prerequisites
 
-Firstly, to enable GDB debugging we need to compile Firecracker with the `debug`
+Firstly, to enable GDB debugging we need to compile Firecracker with the `gdb`
 feature enabled, this will enable the necessary components for the debugging
 process.
 
@@ -102,9 +104,14 @@ command in the GDB session which will terminate both.
   mitigated by setting these kernel config values:
 
   ```
-    CONFIG_SCHED_MC=y
-    CONFIG_SCHED_MC_PRIO=y
+    CONFIG_SCHED_MC=n
+    CONFIG_SCHED_MC_PRIO=n
   ```
 
 - Currently we support a limited subset of cpu registers for get and set
   operations, if more are required feel free to contribute.
+
+- On ARM the guest virtual address translation will only work on guests with 4kb
+  pages and not all physical address sizes are supported. If the current
+  translation implementation doesn't cover a specific setup, feel free to
+  contribute.

tests/integration_tests/build/test_gdb.py

@@ -4,15 +4,12 @@
 
 import platform
 
-import pytest
-
 import host_tools.cargo_build as host
 
 MACHINE = platform.machine()
 TARGET = "{}-unknown-linux-musl".format(MACHINE)
 
 
-@pytest.mark.skipif(MACHINE != "x86_64", reason="GDB runs only on x86_64.")
 def test_gdb_compiles():
     """Checks that Firecracker compiles with GDB enabled"""