[Buildroot] [PATCH 0 of 2 v4] Using gdb in buildroot

@@ -126,5 +126,7 @@ endef
 
 HOST_GDB_POST_INSTALL_HOOKS += HOST_GDB_ADD_SYMLINK
 
+HOST_GDB_POST_INSTALL_HOOKS += gen_gdbinit_file
+
 $(eval $(autotools-package))
 $(eval $(host-autotools-package))

@@ -355,3 +355,10 @@ check_unusable_toolchain = \
 		echo "such as Buildroot." ; \
 		exit 1 ; \
 	fi
+
+#
+# Generate gdbinit file for use with Buildroot
+#
+gen_gdbinit_file = \
+	mkdir -p $(STAGING_DIR)/usr/share/buildroot/ ; \
+	echo "set sysroot $(STAGING_DIR)" > $(STAGING_DIR)/usr/share/buildroot/gdbinit

@@ -651,6 +651,12 @@ define TOOLCHAIN_EXTERNAL_SANITIZE_KERNE
 		-e 's@#(ifndef|define|endif[ \t]*/[*])[ \t]*_UAPI@#\1 @'
 endef
 
+define TOOLCHAIN_EXTERNAL_INSTALL_GDBINIT
+	if test -f $(TARGET_CROSS)gdb ; then \
+		$(call gen_gdbinit_file) ; \
+	fi
+endef
+
 # Even though we're installing things in both the staging, the host
 # and the target directory, we do everything within the
 # install-staging step, arbitrarily.

@@ -659,6 +665,7 @@ define TOOLCHAIN_EXTERNAL_INSTALL_STAGIN
 	$(TOOLCHAIN_EXTERNAL_INSTALL_BFIN_FDPIC)
 	$(TOOLCHAIN_EXTERNAL_INSTALL_BFIN_FLAT)
 	$(TOOLCHAIN_EXTERNAL_INSTALL_WRAPPER)
+	$(TOOLCHAIN_EXTERNAL_INSTALL_GDBINIT)
 endef
 
 $(eval $(generic-package))

@@ -5,6 +5,8 @@
 
 include::using-buildroot-toolchain.txt[]
 
+include::using-buildroot-debugger.txt[]
+
 include::ccache-support.txt[]
 
 include::download-location.txt[]

@@ -0,0 +1,53 @@
+// -*- mode:doc; -*-
+// vim: set syntax=asciidoc:
+
+=== Using +gdb+ in Buildroot
+
+Buildroot allows to do cross-debugging, where the debugger runs on the
+build machine and communicates with +gdbserver+ on the target to
+control the execution of the program.
+
+To achieve this:
+
+* If you are using an _internal toolchain_ (built by Buildroot), you
+  must enable +BR2_PACKAGE_HOST_GDB+, +BR2_PACKAGE_GDB+ and
+  +BR2_PACKAGE_GDB_SERVER+. This ensures that both the cross gdb and
+  gdbserver get built, and that gdbserver gets installed to your target.
+
+* If you are using an _external toolchain_, you should enable
+  +BR2_TOOLCHAIN_EXTERNAL_GDB_SERVER_COPY+, which will copy the
+  gdbserver included with the external toolchain to the target. If your
+  external toolchain does not have a cross gdb or gdbserver, it is also
+  possible to let Buildroot build them, by enabling the same options as
+  for the _internal toolchain backend_.
+
+Now, to start debugging a program called +foo+, you should run on the
+target:
+
+----------------------------
+gdbserver :2345 foo
+----------------------------
+
+This will cause +gdbserver+ to listen on TCP port 2345 for a connection
+from the cross gdb.
+
+Then, on the host, you should start the cross gdb using the following
+command line:
+
+----------------------------
+<buildroot>/output/host/usr/bin/<tuple>-gdb -x <buildroot>/output/staging/usr/share/buildroot/gdbinit foo
+----------------------------
+
+Of course, +foo+ must be available in the current directory, built
+with debugging symbols. Typically you start this command from the
+directory where +foo+ is built (and not from +output/target/+ as the
+binaries in that directory are stripped).
+
+The +<buildroot>/output/staging/usr/share/buildroot/gdbinit+ file will tell the
+cross gdb where to find the libraries of the target.
+
+Finally, to connect to the target from the cross gdb:
+
+----------------------------
+(gdb) target remote <target ip address>:2345
+----------------------------