gdb: add support for Python in target gdb

This commit adds a new option BR2_PACKAGE_GDB_PYTHON to enable Python
support in the target gdb. Since we can assume that the user will be
aware that Python is needed to get Python support in gdb, we chose to
use a "depends on" dependency instead of a "select" dependency.

The other weird thing is the need for a wrapper shell script to
replace gdb's provided python-config.py script. See the shell script
comment itself for all the details.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/package/gdb/gdb-python-config b/package/gdb/gdb-python-config
new file mode 100755
index 0000000000..0f002281d7
--- /dev/null
+++ b/package/gdb/gdb-python-config
@@ -0,0 +1,36 @@
+#!/bin/sh
+
+# This shell script is used to fake Python. Gdb wants to be passed a
+# Python interpreter, to run its own python-config.py program, which
+# uses sysconfig. However, when cross-compiling, this doesn't work
+# well since we would have to use the host Python, whose sysconfig
+# module would return host values.
+#
+# As recommended at
+# https://sourceware.org/gdb/wiki/CrossCompilingWithPythonSupport,
+# this wrapper shell script can be used as a replacement. It ignores
+# the python-config.py script passed as first arguments, and
+# "emulates" its behavior.
+
+if [ $# -ne 2 ] ; then
+    echo "Bad # args." >&2
+    exit 1
+fi
+
+# The first argument is the path to python-config.py, ignore it.
+
+case "$2" in
+    --includes)
+	echo "-I${STAGING_DIR}/usr/include/python2.7"
+	;;
+    --ldflags)
+	echo "-lpthread -ldl -lutil -lm -lpython2.7"
+	;;
+    --exec-prefix)
+	echo "/usr"
+	;;
+    *)
+	echo "Bad arg $2." >&2
+	exit 1
+	;;
+esac