Use buildroot host gdb, consider QEMU and target GDB but give up for now

buildroot_config_fragment

@@ -1,4 +1,35 @@
 BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES="../kernel_config_fragment"
 BR2_PACKAGE_BUSYBOX_CONFIG_FRAGMENT_FILES="../busybox_config_fragment"
 BR2_PACKAGE_KERNEL_MODULE=y
+BR2_PACKAGE_STRACE=y
 BR2_ROOTFS_OVERLAY="../rootfs_overlay"
+
+## Host GDB
+BR2_GDB_VERSION="7.11.1"
+BR2_GDB_VERSION_7_10=n
+BR2_GDB_VERSION_7_11=y
+BR2_GDB_VERSION_7_12=n
+BR2_PACKAGE_HOST_GDB=y
+BR2_PACKAGE_HOST_GDB_PYTHON=y
+BR2_PACKAGE_HOST_GDB_SIM=y
+BR2_PACKAGE_HOST_GDB_TUI=y
+
+## QEMU.
+# Buildroot can also build QEMU, but it does not have SDL support,
+# so you have to mess around with a VNC, so let's not use that for now.
+# Someone should patch this, and add a SDL support option to the QEMU package! :-)
+#BR2_PACKAGE_HOST_QEMU=y
+#BR2_PACKAGE_HOST_QEMU_LINUX_USER_MODE=n
+#BR2_PACKAGE_HOST_QEMU_SYSTEM_MODE=y
+#BR2_PACKAGE_HOST_QEMU_VDE2=y
+
+## Target GDB
+# This is preparation for target GDB / gdbserver.
+# But those options require a toolchain with threads like glibc,
+# which I'm afraid will make compilation slower, so let's leave it
+# at that for now since our focus is kernel debug.
+#BR2_DEBUG_1=n
+#BR2_DEBUG_2=n
+#BR2_DEBUG_3=y
+#BR2_ENABLE_DEBUG=y
+#BR2_OPTIMIZE_0=y

run

@@ -2,6 +2,8 @@
 set -e
 cd buildroot
 make BR2_EXTERNAL="$(pwd)/../kernel_module" qemu_x86_64_defconfig
+# Can't get rid of this for now.
+# http://stackoverflow.com/questions/44078245/is-it-possible-to-use-config-fragments-with-buildroots-config
 cat ../buildroot_config_fragment >> .config
 env -u LD_LIBRARY_PATH make BR2_JLEVEL="$(($(nproc) - 2))" kernel_module-rebuild all
 cd ..

rungdb

@@ -4,8 +4,9 @@ if [ "$#" -gt 0 ]; then
 else
   brk=""
 fi
+gdb="$(pwd)/buildroot/output/host/usr/bin/x86_64-linux-gdb"
 cd buildroot/output/build/linux-*.*.*/
-cmd="gdb \
+cmd="$gdb \
   -q \
   -ex 'add-auto-load-safe-path $(pwd)' \
   -ex 'file vmlinux' \

runqemu

@@ -21,6 +21,8 @@ while getopts dn OPT; do
   esac
 done
 
+# If we turn on buildroot host QEMU some day.
+#cmd="./buildroot/output/host/usr/bin/qemu-system-x86_64 \
 cmd="qemu-system-x86_64 \
   -M pc \
   -append 'root=/dev/vda $extra_append' \