linux.mk: enable options for ktap

Certain tracing related options are required to be able to build ktapvm.ko, enable those.

Enable CONFIG_FUNTCTION_TRACER as otherwise, CONFIG_EVENT_TRACING won't stick. (Some
tracer needs to be enabled for this).

[Peter: add a note to ktap Config.in explaining this is done]
Signed-off-by: Anders Darander <anders@chargestorm.se>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

linux/linux.mk

@@ -184,6 +184,11 @@ define LINUX_CONFIGURE_CMDS
 		$(call KCONFIG_ENABLE_OPT,CONFIG_DEVTMPFS_MOUNT,$(@D)/.config))
 	$(if $(BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_MDEV),
 		$(call KCONFIG_SET_OPT,CONFIG_UEVENT_HELPER_PATH,\"/sbin/mdev\",$(@D)/.config))
+	$(if $(BR2_PACKAGE_KTAP),
+		$(call KCONFIG_ENABLE_OPT,CONFIG_DEBUG_FS,$(@D)/.config)
+		$(call KCONFIG_ENABLE_OPT,CONFIG_EVENT_TRACING,$(@D)/.config)
+		$(call KCONFIG_ENABLE_OPT,CONFIG_PERF_EVENTS,$(@D)/.config)
+		$(call KCONFIG_ENABLE_OPT,CONFIG_FUNCTION_TRACER,$(@D)/.config))
 	$(if $(BR2_PACKAGE_SYSTEMD),
 		$(call KCONFIG_ENABLE_OPT,CONFIG_CGROUPS,$(@D)/.config))
 	$(if $(BR2_LINUX_KERNEL_APPENDED_DTB),

package/ktap/Config.in

@@ -16,6 +16,8 @@ config BR2_PACKAGE_KTAP
 	  Your kernel must have CONFIG_EVENT_TRACING,
 	  CONFIG_PERF_EVENTS, and CONFIG_DEBUG_FS enabled to compile.
 
+	  Buildroot automatically enables these in the kernel configuration.
+
 	  http://www.ktap.org
 
 comment "ktap needs a Linux kernel to be built"