support/testing: add FLAT stack size test case

Add an infrastructure test case to verify that the per-package
<PKG>_FLAT_STACKSIZE variable correctly configures the stack size in the
generated FLAT binary header.

Signed-off-by: Fengwei Tan <tfx2001@outlook.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 0bf4525045)
Signed-off-by: Raphaël Mélotte <raphael.melotte@mind.be>

DEVELOPERS

@@ -1074,6 +1074,9 @@ F:	configs/freescale_imx6ullevk_defconfig
 N:	Falco Hyfing <hyfinglists@gmail.com>
 F:	package/python-pymodbus/
 
+N:	Fengwei Tan <tfx2001@outlook.com>
+F:	support/testing/tests/core/test_flat_stacksize.py
+
 N:	Fiona Klute <fiona.klute@gmx.de>
 F:	package/*/S*
 F:	package/panel-mipi-dbi-firmware/

support/testing/tests/core/br2-external/flat-stacksize/Config.in

@@ -0,0 +1 @@
+source "$BR2_EXTERNAL_FLAT_STACKSIZE_PATH/package/flat-stacksize-test/Config.in"

support/testing/tests/core/br2-external/flat-stacksize/external.desc

@@ -0,0 +1 @@
+name: FLAT_STACKSIZE

support/testing/tests/core/br2-external/flat-stacksize/external.mk

@@ -0,0 +1 @@
+include $(sort $(wildcard $(BR2_EXTERNAL_FLAT_STACKSIZE_PATH)/package/*/*.mk))

support/testing/tests/core/br2-external/flat-stacksize/package/flat-stacksize-test/Config.in

@@ -0,0 +1,7 @@
+config BR2_PACKAGE_FLAT_STACKSIZE_TEST
+	bool "flat-stacksize-test"
+	depends on BR2_BINFMT_FLAT && !BR2_USE_MMU
+	help
+	  Package for testing the $(PKG)_FLAT_STACKSIZE variable, which
+	  defines the stack size of an application built into the
+	  FLAT binary format.

support/testing/tests/core/br2-external/flat-stacksize/package/flat-stacksize-test/Makefile

@@ -0,0 +1,15 @@
+O ?= $(CURDIR)
+
+CANONICAL_O := $(shell mkdir -p $(O) >/dev/null 2>&1)$(realpath $(O))
+
+TARGET := $(CANONICAL_O)/flat_stacksize_test
+
+all: $(TARGET)
+
+$(TARGET): main.c
+	$(CC) $(CFLAGS) -o $@ main.c
+
+clean:
+	rm -f $(TARGET)
+
+.PHONY: all clean

support/testing/tests/core/br2-external/flat-stacksize/package/flat-stacksize-test/flat-stacksize-test.mk

@@ -0,0 +1,22 @@
+################################################################################
+#
+# flat-stacksize-test
+#
+################################################################################
+
+# Define a stack size that is different from the default FLAT
+# stack size (4096 bytes).
+FLAT_STACKSIZE_TEST_FLAT_STACKSIZE = 8192
+
+define FLAT_STACKSIZE_TEST_BUILD_CMDS
+	$(TARGET_MAKE_ENV) $(MAKE) \
+		-C $(FLAT_STACKSIZE_TEST_PKGDIR) O=$(@D) \
+		$(TARGET_CONFIGURE_OPTS)
+endef
+
+define FLAT_STACKSIZE_TEST_INSTALL_TARGET_CMDS
+	$(INSTALL) -D -m 0755 $(@D)/flat_stacksize_test \
+		$(TARGET_DIR)/usr/bin/flat_stacksize_test
+endef
+
+$(eval $(generic-package))

support/testing/tests/core/br2-external/flat-stacksize/package/flat-stacksize-test/main.c

@@ -0,0 +1,3 @@
+int main(void) {
+    return 0;
+}

support/testing/tests/core/test_flat_stacksize.py

@@ -0,0 +1,27 @@
+import os
+
+import infra.basetest
+
+
+class TestFlatStackSize(infra.basetest.BRTest):
+    br2_external = [infra.filepath("tests/core/br2-external/flat-stacksize")]
+    config = """
+        BR2_arm=y
+        BR2_cortex_m4=y
+        BR2_TOOLCHAIN_EXTERNAL=y
+        BR2_TOOLCHAIN_EXTERNAL_BOOTLIN=y
+        BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_ARMV7M_UCLIBC_STABLE=y
+        # BR2_TARGET_ROOTFS_TAR is not set
+        BR2_PACKAGE_FLAT_STACKSIZE_TEST=y
+        """
+
+    def test_run(self):
+        binary = os.path.join(
+            self.builddir, "target", "usr", "bin", "flat_stacksize_test"
+        )
+        self.assertTrue(os.path.exists(binary))
+
+        # Check the FLAT binary header really carries the stack size
+        # declared by the package (8192 = 0x2000).
+        out = infra.run_cmd_on_host(self.builddir, ["arm-linux-flthdr", binary])
+        self.assertIn("Stack Size:   0x2000\n", out)