Build userland examples separately

README.adoc

@@ -1602,7 +1602,7 @@ We can set and get which cores the Linux kernel allows a program to run on with
 ./run --cpus 2 --eval-busybox '/sched_getaffinity.out'
 ....
 
-Source: link:packages/kernel_modules/user/sched_getaffinity.c[]
+Source: link:packages/kernel_modules/userland/sched_getaffinity.c[]
 
 Sample output:
 
@@ -2108,7 +2108,7 @@ Sources:
 
 * link:packages/kernel_modules/ring0.c[]
 * link:packages/kernel_modules/ring0.h[]
-* link:packages/kernel_modules/user/ring0.c[]
+* link:packages/kernel_modules/userland/ring0.c[]
 
 In both cases, we attempt to run the exact same code which is shared on the `ring0.h` header file.
 
@@ -2258,7 +2258,7 @@ but why not just use our minimal `/poweroff.out` and be done with it?
 ./run --eval '/poweroff.out'
 ....
 
-Source: link:packages/kernel_modules/user/poweroff.c[]
+Source: link:packages/kernel_modules/userland/poweroff.c[]
 
 This also illustrates how to shutdown the computer from C: https://stackoverflow.com/questions/28812514/how-to-shutdown-linux-using-c-or-qt-without-call-to-system
 
@@ -2270,7 +2270,7 @@ I dare you to guess what this does:
 ./run --eval '/sleep_forever.out'
 ....
 
-Source: link:packages/kernel_modules/user/sleep_forever.c[]
+Source: link:packages/kernel_modules/userland/sleep_forever.c[]
 
 This executable is a convenient simple init that does not panic and sleeps instead.
 
@@ -2363,7 +2363,7 @@ TERM=linux
 asdf=qwer
 ....
 
-Source: link:packages/kernel_modules/user/init_env_poweroff.c[].
+Source: link:packages/kernel_modules/userland/init_env_poweroff.c[].
 
 ==== init environment args
 
@@ -2790,8 +2790,8 @@ which teaches you how it is done from C code.
 
 Source:
 
-* link:packages/kernel_modules/user/myinsmod.c[]
-* link:packages/kernel_modules/user/myrmmod.c[]
+* link:packages/kernel_modules/userland/myinsmod.c[]
+* link:packages/kernel_modules/userland/myrmmod.c[]
 
 The Linux kernel offers two system calls for module insertion:
 
@@ -4763,7 +4763,7 @@ Sources:
 
 * link:packages/kernel_modules/ioctl.c[]
 * link:packages/kernel_modules/ioctl.h[]
-* link:packages/kernel_modules/user/ioctl.c[]
+* link:packages/kernel_modules/userland/ioctl.c[]
 * link:rootfs_overlay/ioctl.sh[]
 
 `ioctl` is one of the most important methods of communication with real device drivers, which often take several fields as input.
@@ -4811,7 +4811,7 @@ Outcome: the test passes:
 Sources:
 
 * link:packages/kernel_modules/mmap.c[]
-* link:packages/kernel_modules/user/mmap.c[]
+* link:packages/kernel_modules/userland/mmap.c[]
 * link:rootfs_overlay/mmap.sh[]
 
 In this example, we make a tiny 4 byte kernel buffer available to user-space, and we then modify it on userspace, and check that the kernel can see the modification.
@@ -4848,7 +4848,7 @@ Sources:
 
 * link:packages/kernel_modules/anonymous_inode.c[]
 * link:packages/kernel_modules/anonymous_inode.h[]
-* link:packages/kernel_modules/user/anonymous_inode.c[]
+* link:packages/kernel_modules/userland/anonymous_inode.c[]
 * link:rootfs_overlay/anonymous_inode.sh[]
 
 This example gets an anonymous inode via <<ioctl>> from a debugfs entry by using `anon_inode_getfd`.
@@ -4876,7 +4876,7 @@ Sources:
 
 * link:packages/kernel_modules/netlink.c[]
 * link:packages/kernel_modules/netlink.h[]
-* link:packages/kernel_modules/user/netlink.c[]
+* link:packages/kernel_modules/userland/netlink.c[]
 * link:rootfs_overlay/netlink.sh[]
 
 Launch multiple user requests in parallel to stress our socket:
@@ -5354,7 +5354,7 @@ First get a virtual address to play with:
 /virt_to_phys_test.out &
 ....
 
-Source: link:packages/kernel_modules/user/virt_to_phys_test.c[]
+Source: link:packages/kernel_modules/userland/virt_to_phys_test.c[]
 
 Sample output:
 
@@ -5381,7 +5381,7 @@ Sample output physical address:
 0x7c7b800
 ....
 
-Source: link:packages/kernel_modules/user/virt_to_phys_user.c[]
+Source: link:packages/kernel_modules/userland/virt_to_phys_user.c[]
 
 Now we can verify that `virt_to_phys_user.out` gave the correct physical address in the following ways:
 
@@ -5498,7 +5498,7 @@ vaddr pfn soft-dirty file/shared swapped present library
 7ffff78ec000 1fd4 0 1 0 1 /lib/libuClibc-1.0.30.so
 ....
 
-Source: link:packages/kernel_modules/user/pagemap_dump.c[]
+Source: link:packages/kernel_modules/userland/pagemap_dump.c[]
 
 Adapted from: https://github.com/dwks/pagemap/blob/8a25747bc79d6080c8b94eac80807a4dceeda57a/pagemap2.c
 
@@ -5593,7 +5593,7 @@ a
 #
 ....
 
-Source: link:packages/kernel_modules/user/proc_events.c[]
+Source: link:packages/kernel_modules/userland/proc_events.c[]
 
 TODO: why `exit: tid=79` shows after `exit: tid=80`?
 
@@ -6003,7 +6003,7 @@ UIO interface in a nutshell:
 
 Sources:
 
-* link:packages/kernel_modules/user/uio_read.c[]
+* link:packages/kernel_modules/userland/uio_read.c[]
 * link:rootfs_overlay/uio_read.sh[]
 
 Bibliography:
@@ -6134,7 +6134,7 @@ Minimal example:
 ./run --kernel-cli 'init=/ctrl_alt_del.out' --graphic
 ....
 
-Source: link:packages/kernel_modules/user/ctrl_alt_del.c[]
+Source: link:packages/kernel_modules/userland/ctrl_alt_del.c[]
 
 When you hit `Ctrl-Alt-Del` in the guest, our tiny init handles a `SIGINT` sent by the kernel and outputs to stdout:
 
@@ -6444,11 +6444,12 @@ Looks like a recompile is needed to modify the image...
 DRM / DRI is the new interface that supersedes `fbdev`:
 
 ....
-./build-buildroot --buildroot-config 'BR2_PACKAGE_LIBDRM=y' --kernel-modules
+./build-buildroot --buildroot-config 'BR2_PACKAGE_LIBDRM=y'
+./build-userland --has-package libdrm -- libdrm_modeset
 ./run --eval-busybox '/libdrm_modeset.out' --graphic
 ....
 
-Source: link:packages/kernel_modules/user/libdrm_modeset.c[]
+Source: link:packages/kernel_modules/userland/libdrm_modeset.c[]
 
 Outcome: for a few seconds, the screen that contains the terminal gets taken over by changing colors of the rainbow.
 
@@ -8409,7 +8410,7 @@ and then feed `bst_vs_heap.dat` into: https://github.com/cirosantilli/cpp-cheat/
 Sources:
 
 * link:bst-vs-heap[]
-* link:packages/kernel_modules/user/bst_vs_heap.cpp[]
+* link:packages/kernel_modules/userland/bst_vs_heap.cpp[]
 
 ===== OpenMP
 
@@ -8419,15 +8420,16 @@ Implemented by GCC itself, so just a toolchain configuration, no external libs,
 /openmp.out
 ....
 
-Source: link:packages/kernel_modules/user/openmp.c[]
+Source: link:packages/kernel_modules/userland/openmp.c[]
 
 ===== BLAS
 
 Buildroot supports it, which makes everything just trivial:
 
 ....
-./build-buildroot --buildroot-config 'BR2_PACKAGE_OPENBLAS=y' --kernel-modules
-./run --eval-busybox '/openblas.out; echo $?'
+./build-buildroot --buildroot-config 'BR2_PACKAGE_OPENBLAS=y'
+./build-userland --has-package openblas -- openblas_hello
+./run --eval-busybox '/openblas_hello.out; echo $?'
 ....
 
 Outcome: the test passes:
@@ -8436,7 +8438,7 @@ Outcome: the test passes:
 0
 ....
 
-Source: link:packages/kernel_modules/user/openblas.c[]
+Source: link:packages/kernel_modules/userland/openblas.c[]
 
 The test performs a general matrix multiplication:
 
@@ -8465,13 +8467,14 @@ cblas_dgemm(      CblasColMajor, CblasNoTrans, CblasTrans,3,3,2  ,1,    A,3,  B,
 Header only linear algebra library with a mainline Buildroot package:
 
 ....
-./build-buildroot --buildroot-config 'BR2_PACKAGE_EIGEN=y' --kernel-modules
+./build-buildroot --buildroot-config 'BR2_PACKAGE_EIGEN=y'
+./build-userland --has-package eigen -- eigen_hello
 ....
 
 Just create an array and print it:
 
 ....
-./run --eval-busybox '/eigen.out'
+./run --eval-busybox '/eigen_hello.out'
 ....
 
 Output:
@@ -8481,7 +8484,7 @@ Output:
 2.5 1.5
 ....
 
-Source: link:packages/kernel_modules/user/eigen.cpp[]
+Source: link:packages/kernel_modules/userland/eigen_hello.cpp[]
 
 This example just creates a matrix and prints it out.
 
@@ -9167,8 +9170,8 @@ The executable `/m5ops.out` illustrates how to hard code with inline assembly th
 
 Sources:
 
-* link:packages/kernel_modules/user/m5ops.h[]
-* link:packages/kernel_modules/user/m5ops.c[]
+* link:packages/kernel_modules/userland/m5ops.h[]
+* link:packages/kernel_modules/userland/m5ops.c[]
 
 That executable is of course a subset of <<m5>> and useless by itself: its goal is only illustrate how to hardcode some <<m5ops>> yourself as one-liners.
 
@@ -9310,13 +9313,14 @@ system.cpu.dtb.inst_hits
 Let's have some fun and try to correlate the gem5 cycle count `system.cpu.numCycles` with the link:https://en.wikipedia.org/wiki/Time_Stamp_Counter[x86 `rdtsc` instruction] that is supposed to do the same thing:
 
 ....
-./build-buildroot --gem5 --kernel-modules && \
+./build-buildroot --gem5 && \
+./build-userland -- rdtsc && \
 ./run --eval '/rdtsc.out;m5 exit;' --gem5 && \
 ./gem5-stat && \
 :;
 ....
 
-Source: link:packages/kernel_modules/user/rdtsc.c[]
+Source: link:packages/kernel_modules/userland/rdtsc.c[]
 
 `rdtsc` outputs a cycle count which we compare with gem5's `gem5-stat`:
 
@@ -11024,8 +11028,8 @@ hello cpp
 
 Sources:
 
-* link:packages/kernel_modules/user/hello.c[]
-* link:packages/kernel_modules/user/hello_cpp.c[]
+* link:packages/kernel_modules/userland/hello.c[]
+* link:packages/kernel_modules/userland/hello_cpp.c[]
 
 ==== rand_check.out
 
@@ -11035,7 +11039,7 @@ Print out several parameters that normally change randomly from boot to boot:
 ./run --eval-busybox '/rand_check.out;/poweroff.out'
 ....
 
-Source: link:packages/kernel_modules/user/rand_check.c[]
+Source: link:packages/kernel_modules/userland/rand_check.c[]
 
 This can be used to check the determinism of:
 

build-modules

@@ -10,7 +10,9 @@ import time
 
 import common
 
-parser = common.get_argparse()
+parser = common.get_argparse(argparse_args={
+    'description': 'Build our Linux kernel module examples'
+})
 common.add_build_arguments(parser)
 parser.add_argument(
     '--host',
@@ -35,9 +37,6 @@ if args.clean:
 else:
     start_time = time.time()
     os.makedirs(build_dir, exist_ok=True)
-
-    # Build kernel modules.
-    #
     # I kid you not, out-of-tree build is not possible, O= does not work as for the kernel build:
     #
     # * https://stackoverflow.com/questions/5718899/building-an-out-of-tree-linux-kernel-module-in-a-separate-object-directory
@@ -99,24 +98,5 @@ else:
         ),
         cwd=common.kernel_modules_src_dir,
     ) == 0
-
-    # Build userland tools.
-    if args.host:
-        allowed_toolchains = ['host']
-    else:
-        allowed_toolchains = ['buildroot']
-    cc = common.get_toolchain_tool('gcc', allowed_toolchains=allowed_toolchains)
-    cxx = common.get_toolchain_tool('g++', allowed_toolchains=allowed_toolchains)
-    assert common.run_cmd(
-        [
-            'make',
-            '-j', str(multiprocessing.cpu_count()),
-            'CC={}'.format(cc),
-            'CXX={}'.format(cxx),
-            'OUT_DIR={}'.format(os.path.join(build_dir, 'user')),
-        ],
-        cwd=os.path.join(common.kernel_modules_src_dir, 'user'),
-        extra_paths=[common.ccache_dir],
-    ) == 0
     end_time = time.time()
     common.print_time(end_time - start_time)

build-userland

@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+
+import distutils.file_util
+import multiprocessing
+import os
+import platform
+import shutil
+import subprocess
+import time
+
+import common
+
+parser = common.get_argparse(argparse_args={
+    'description': 'Build our compiled userland examples',
+})
+common.add_build_arguments(parser)
+parser.add_argument(
+    '--has-package',
+    action='append',
+    default=[],
+    help='''\
+Indicate that a given package is present in the root filesystem, which
+allows us to build examples that rely on it.
+''',
+)
+parser.add_argument(
+    'targets',
+    default=[],
+    help='''\
+Build only the given userland programs.
+Default: build all examples that have their package dependencies met.
+For example, an OpenBLAS example can only be built if the target root filesystem
+has the OpenBLAS libraries and headers installed.
+''',
+    metavar='programs',
+    nargs='*',
+)
+args = common.setup(parser)
+if args.clean:
+    common.rmrf(common.userland_build_dir)
+else:
+    start_time = time.time()
+    os.makedirs(common.userland_build_dir, exist_ok=True)
+    allowed_toolchains = ['buildroot']
+    cc = common.get_toolchain_tool('gcc', allowed_toolchains=allowed_toolchains)
+    cxx = common.get_toolchain_tool('g++', allowed_toolchains=allowed_toolchains)
+    assert common.run_cmd(
+        (
+            [
+                'make',
+                '-j', str(multiprocessing.cpu_count()),
+                'CC={}'.format(cc),
+                'CXX={}'.format(cxx),
+                'PKG_CONFIG={}'.format(common.buildroot_pkg_config),
+                'STAGING_DIR={}'.format(common.buildroot_staging_dir),
+                'OUT_DIR={}'.format(common.userland_build_dir),
+            ] +
+            ['HAS_{}=y'.format(package.upper()) for package in args.has_package] +
+            [os.path.join(common.userland_build_dir, os.path.splitext(os.path.split(target)[1])[0]) + common.executable_ext for target in args.targets]
+        ),
+        cwd=common.userland_src_dir,
+        extra_paths=[common.ccache_dir],
+    ) == 0
+    end_time = time.time()
+    common.print_time(end_time - start_time)

common.py

@@ -28,6 +28,7 @@ out_dir = os.path.join(root_dir, 'out')
 bench_boot = os.path.join(out_dir, 'bench-boot.txt')
 packages_dir = os.path.join(root_dir, 'packages')
 kernel_modules_src_dir = os.path.join(this.packages_dir, 'kernel_modules')
+userland_src_dir = os.path.join(this.kernel_modules_src_dir, 'userland')
 submodules_dir = os.path.join(root_dir, 'submodules')
 buildroot_src_dir = os.path.join(submodules_dir, 'buildroot')
 crosstool_ng_src_dir = os.path.join(submodules_dir, 'crosstool-ng')
@@ -53,6 +54,7 @@ asm_ext = '.S'
 c_ext = '.c'
 kernel_module_ext = '.ko'
 obj_ext = '.o'
+executable_ext = '.out'
 config_file = os.path.join(data_dir, 'config')
 if os.path.exists(config_file):
     config = imp.load_source('config', config_file)
@@ -548,10 +550,12 @@ def setup(parser):
     this.qemu_guest_build_dir = os.path.join(this.build_dir, 'qemu-custom')
     this.host_dir = os.path.join(this.buildroot_build_dir, 'host')
     this.host_bin_dir = os.path.join(this.host_dir, 'usr', 'bin')
+    this.buildroot_pkg_config = os.path.join(this.host_bin_dir, 'pkg-config')
     this.buildroot_images_dir = os.path.join(this.buildroot_build_dir, 'images')
     this.rootfs_raw_file = os.path.join(this.buildroot_images_dir, 'rootfs.ext2')
     this.qcow2_file = this.rootfs_raw_file + '.qcow2'
-    this.staging_dir = os.path.join(this.buildroot_build_dir, 'staging')
+    this.staging_dir = os.path.join(this.out_dir, 'staging', args.arch)
+    this.buildroot_staging_dir = os.path.join(this.buildroot_build_dir, 'staging')
     this.target_dir = os.path.join(this.buildroot_build_dir, 'target')
     this.run_dir_base = os.path.join(this.out_dir, 'run')
     this.gem5_run_dir = os.path.join(this.run_dir_base, 'gem5', args.arch, str(args.run_id))
@@ -627,6 +631,7 @@ def setup(parser):
     this.kernel_modules_build_base_dir = os.path.join(this.out_dir, 'kernel_modules')
     this.kernel_modules_build_dir = os.path.join(this.kernel_modules_build_base_dir, args.arch)
     this.kernel_modules_build_host_dir = os.path.join(this.kernel_modules_build_base_dir, 'host')
+    this.userland_build_dir = os.path.join(this.out_dir, 'userland', args.arch)
 
     # Ports
     if args.port_offset is None:

packages/kernel_modules/Makefile

@@ -1,4 +1,13 @@
+ifeq ($(OBJECT_FILES),)
+obj-m += $(addsuffix .o, $(notdir $(basename $(filter-out %.mod.c, $(wildcard $(BR2_EXTERNAL_KERNEL_MODULES_PATH)/*.c)))))
+else
+# Trying to do:
+# $(MAKE) -C '$(LINUX_DIR)' M='$(M)' hello.ko hello2.ko
+# to restrict which modules are built leads to failures
+# when doing parallel builds. The only solution I could find
+# was to let the host select obj-m itself.
 obj-m += $(OBJECT_FILES)
+endif
 ccflags-y := -DDEBUG -g -std=gnu99 -Werror -Wno-declaration-after-statement -Wframe-larger-than=1000000000
 
 .PHONY: all

packages/kernel_modules/external.mk

@@ -19,10 +19,10 @@ ifeq ($(BR2_PACKAGE_OPENBLAS),y)
 endif
 
 define KERNEL_MODULES_BUILD_CMDS
-	$(MAKE) -C '$(@D)/user' $(TARGET_CONFIGURE_OPTS) \
-	  BR2_PACKAGE_EIGEN="$(BR2_PACKAGE_EIGEN)" \
-	  BR2_PACKAGE_LIBDRM="$(BR2_PACKAGE_LIBDRM)" \
-	  BR2_PACKAGE_OPENBLAS="$(BR2_PACKAGE_OPENBLAS)" \
+	$(MAKE) -C '$(@D)/userland' $(TARGET_CONFIGURE_OPTS) \
+	  HAS_EIGEN="$(BR2_PACKAGE_EIGEN)" \
+	  HAS_LIBDRM="$(BR2_PACKAGE_LIBDRM)" \
+	  HAS_OPENBLAS="$(BR2_PACKAGE_OPENBLAS)" \
 	;
 endef
 
@@ -33,7 +33,7 @@ define KERNEL_MODULES_INSTALL_TARGET_CMDS
 	#
 	# Modules can be still be easily inserted with "modprobe module" however.
 	$(INSTALL) -D -m 0655 $(@D)/*.ko '$(TARGET_DIR)'
-	$(INSTALL) -D -m 0755 $(@D)/user/*.out '$(TARGET_DIR)'
+	$(INSTALL) -D -m 0755 $(@D)/userland/*.out '$(TARGET_DIR)'
 endef
 
 $(eval $(kernel-module))

packages/kernel_modules/user/README.adoc

@@ -1,3 +0,0 @@
-https://github.com/cirosantilli/linux-kernel-module-cheat#rootfs_overlay
-
-. link:sched_getaffinity.c[]

packages/kernel_modules/userland/Makefile

@@ -10,7 +10,7 @@ OUT_EXT = .out
 OUT_DIR = .
 
 OUTS := $(foreach IN_EXT,$(IN_EXT_C) $(IN_EXT_CXX),$(addsuffix $(OUT_EXT), $(basename $(wildcard *$(IN_EXT)))))
-ifeq ($(BR2_PACKAGE_EIGEN),y)
+ifeq ($(HAS_EIGEN),y)
 	CXXFLAGS_EXTRA += -I$(STAGING_DIR)/usr/include/eigen3
 	# TODO: was failing with:
 	# fatal error: Eigen/Dense: No such file or directory as of
@@ -20,26 +20,27 @@ ifeq ($(BR2_PACKAGE_EIGEN),y)
 else
 	OUTS := $(filter-out eigen_%$(OUT_EXT),$(OUTS))
 endif
-ifeq ($(BR2_PACKAGE_LIBDRM),y)
+ifeq ($(HAS_LIBDRM),y)
 	LIBS += $(shell $(PKG_CONFIG) --libs libdrm)
 	CFLAGS_EXTRA += $(shell $(PKG_CONFIG) --cflags libdrm)
 else
 	OUTS := $(filter-out libdrm_%$(OUT_EXT),$(OUTS))
 endif
-ifeq ($(BR2_PACKAGE_OPENBLAS),y)
-	LIBS += -lopenblas
+ifeq ($(HAS_OPENBLAS),y)
+	LIBS += $(shell $(PKG_CONFIG) --libs openblas)
+	CFLAGS_EXTRA += $(shell $(PKG_CONFIG) --cflags openblas)
 else
-	OUTS := $(filter-out openblas$(OUT_EXT),$(OUTS))
+	OUTS := $(filter-out openblas_%$(OUT_EXT),$(OUTS))
 endif
 OUTS := $(addprefix $(OUT_DIR)/,$(OUTS))
 
 all: mkdir $(OUTS)
 
 $(OUT_DIR)/%$(OUT_EXT): %$(IN_EXT_C)
-	$(CC) $(CFLAGS) $(CFLAGS_EXTRA) -o '$@' '$<' $(LIBS)
+	$(CC) $(CFLAGS) $(CCFLAGS) $(CFLAGS_EXTRA) -o '$@' '$<' $(LIBS)
 
 $(OUT_DIR)/%$(OUT_EXT): %$(IN_EXT_CXX)
-	$(CXX) $(CXXFLAGS) $(CXXFLAGS_EXTRA) -o '$@' '$<' $(LIBS)
+	$(CXX) $(CXXFLAGS) $(CCFLAGS) $(CXXFLAGS_EXTRA) -o '$@' '$<' $(LIBS)
 
 clean:
 	rm -f *'$(OUT_EXT)'

packages/kernel_modules/userland/external.desc

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

packages/kernel_modules/userland/external.mk

@@ -0,0 +1,34 @@
+################################################################################
+#
+# kernel_modules
+#
+################################################################################
+
+KERNEL_MODULES_VERSION = 1.0
+KERNEL_MODULES_SITE = $(BR2_EXTERNAL_KERNEL_MODULES_PATH)
+KERNEL_MODULES_SITE_METHOD = local
+
+ifeq ($(BR2_PACKAGE_EIGEN),y)
+	KERNEL_MODULES_DEPENDENCIES += eigen
+endif
+ifeq ($(BR2_PACKAGE_LIBDRM),y)
+	KERNEL_MODULES_DEPENDENCIES += libdrm
+endif
+ifeq ($(BR2_PACKAGE_OPENBLAS),y)
+	KERNEL_MODULES_DEPENDENCIES += openblas
+endif
+
+define KERNEL_MODULES_BUILD_CMDS
+	$(MAKE) -C '$(@D)' $(TARGET_CONFIGURE_OPTS) \
+	  BR2_PACKAGE_EIGEN="$(BR2_PACKAGE_EIGEN)" \
+	  BR2_PACKAGE_LIBDRM="$(BR2_PACKAGE_LIBDRM)" \
+	  BR2_PACKAGE_OPENBLAS="$(BR2_PACKAGE_OPENBLAS)" \
+	;
+endef
+
+define KERNEL_MODULES_INSTALL_TARGET_CMDS
+	$(INSTALL) -D -m 0755 $(@D)/*.out '$(TARGET_DIR)'
+endef
+
+$(eval $(kernel-module))
+$(eval $(generic-package))

packages/kernel_modules/userland/netlink.c

@@ -20,7 +20,7 @@ struct msghdr msg;
 struct nlmsghdr *nlh;
 struct sockaddr_nl src_addr, dest_addr;
 
-int main()
+int main(void)
 {
 	sock_fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_USER);
 	if (sock_fd < 0) {

packages/kernel_modules/userland/openblas_hello.c

@@ -6,7 +6,7 @@
 #include <assert.h>
 #include <cblas.h>
 
-int main()
+int main(void)
 {
 	double A[6] = {1.0, 2.0, 1.0, -3.0, 4.0, -1.0};
 	double B[6] = {1.0, 2.0, 1.0, -3.0, 4.0, -1.0};

packages/kernel_modules/userland/proc_events.c

@@ -5,7 +5,7 @@
 
 #if defined(__aarch64__)
 
-int main() {}
+int main(void) {}
 
 #else
 
@@ -147,7 +147,7 @@ static void on_sigint(__attribute__ ((unused)) int unused)
 	need_exit = true;
 }
 
-int main()
+int main(void)
 {
 	int nl_sock;
 	int rc = EXIT_SUCCESS;

packages/kernel_modules/userland/uio_read.c

@@ -66,7 +66,7 @@ int main(int argc, char **argv)
 #include <unistd.h>
 #include <unistd.h>
 
-int main()
+int main(void)
 {
     int uiofd;
     int configfd;

run-gdbserver

@@ -18,7 +18,7 @@ args = common.setup(parser)
 sys.exit(subprocess.Popen([
   common.get_toolchain_tool('gdb'),
   '-q',
-  '-ex', 'set sysroot {}'.format(common.staging_dir),
+  '-ex', 'set sysroot {}'.format(common.buildroot_staging_dir),
   '-ex', 'target remote localhost:{}'.format(common.qemu_hostfwd_generic_port),
   '-ex', 'tbreak main',
   '-ex', 'continue',