Ubuntu 18.04 compile error at x84 idle.c

[HHPLow]

Hi @cl91 @lsf37
When I following the seL4 doc to build Stand-alone seL4 and seL4test
Will meet compile error like below

seL4_build# ninja kernel.elf
[33/34] Building C object CMakeFiles/kernel.elf.dir/kernel_all.c.obj
FAILED: CMakeFiles/kernel.elf.dir/kernel_all.c.obj
/usr/bin/ccache /usr/bin/gcc --sysroot=/ws/seL4_build  -I/ws/seL4/include -I/ws/seL4/include/64 -I/ws/seL4/include/arch/x86 -I/ws/seL4/include/arch/x86/arch/64 -I/ws/seL4/include/plat/pc99 -I/ws/seL4/include/plat/pc99/plat/64 -I/ws/seL4/libsel4/include -I/ws/seL4/libsel4/arch_include/x86 -I/ws/seL4/libsel4/sel4_arch_include/x86_64 -I/ws/seL4/libsel4/sel4_plat_include/pc99 -I/ws/seL4/libsel4/mode_include/64 -I/ws/seL4_build/gen_config -I/ws/seL4_build/autoconf -I/ws/seL4_build/gen_headers -I/ws/seL4_build/generated -m64  -march=nehalem -D__KERNEL_64__ -O3 -DNDEBUG -nostdinc -nostdlib -O2 -DHAVE_AUTOCONF -mcmodel=kernel -fno-pic -fno-pie -fno-stack-protector -fno-asynchronous-unwind-tables -std=c99 -Wall -Werror -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Wmissing-declarations -Wundef -Wpointer-arith -Wno-nonnull -ffreestanding -fno-common -mno-mmx -mno-sse -mno-sse2 -mno-3dnow -MD -MT CMakeFiles/kernel.elf.dir/kernel_all.c.obj -MF CMakeFiles/kernel.elf.dir/kernel_all.c.obj.d -o CMakeFiles/kernel.elf.dir/kernel_all.c.obj -c /ws/seL4_build/kernel_all.c
/ws/seL4/src/arch/x86/idle.c:17:1: error: ‘naked’ attribute directive ignored [-Werror=attributes]
 {
 ^
/ws/seL4/src/arch/x86/idle.c: In function ‘idle_thread’:
/ws/seL4/src/arch/x86/idle.c:25:1: error: ‘noreturn’ function does return [-Werror]
 }
 ^
cc1: all warnings being treated as errors
ninja: build stopped: subcommand failed.

When I remove the NORETURN, still error

seL4_build# ninja kernel.elf
[21/22] Building C object CMakeFiles/kernel.elf.dir/kernel_all.c.obj
FAILED: CMakeFiles/kernel.elf.dir/kernel_all.c.obj
/usr/bin/ccache /usr/bin/gcc --sysroot=/ws/seL4_build  -I/ws/seL4/include -I/ws/seL4/include/64 -I/ws/seL4/include/arch/x86 -I/ws/seL4/include/arch/x86/arch/64 -I/ws/seL4/include/plat/pc99 -I/ws/seL4/include/plat/pc99/plat/64 -I/ws/seL4/libsel4/include -I/ws/seL4/libsel4/arch_include/x86 -I/ws/seL4/libsel4/sel4_arch_include/x86_64 -I/ws/seL4/libsel4/sel4_plat_include/pc99 -I/ws/seL4/libsel4/mode_include/64 -I/ws/seL4_build/gen_config -I/ws/seL4_build/autoconf -I/ws/seL4_build/gen_headers -I/ws/seL4_build/generated -m64  -march=nehalem -D__KERNEL_64__ -O3 -DNDEBUG -nostdinc -nostdlib -O2 -DHAVE_AUTOCONF -mcmodel=kernel -fno-pic -fno-pie -fno-stack-protector -fno-asynchronous-unwind-tables -std=c99 -Wall -Werror -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Wmissing-declarations -Wundef -Wpointer-arith -Wno-nonnull -ffreestanding -fno-common -mno-mmx -mno-sse -mno-sse2 -mno-3dnow -MD -MT CMakeFiles/kernel.elf.dir/kernel_all.c.obj -MF CMakeFiles/kernel.elf.dir/kernel_all.c.obj.d -o CMakeFiles/kernel.elf.dir/kernel_all.c.obj -c /ws/seL4_build/kernel_all.c
/ws/seL4/src/arch/x86/idle.c:17:1: error: ‘naked’ attribute directive ignored [-Werror=attributes]
 {
 ^
cc1: all warnings being treated as errors
ninja: build stopped: subcommand failed.

until I change this file to

diff --git a/src/arch/x86/idle.c b/src/arch/x86/idle.c
index 82bd30b6..c0a8cc88 100644
--- a/src/arch/x86/idle.c
+++ b/src/arch/x86/idle.c
@@ -13,7 +13,7 @@
  * always eliminates the function prologue by declaring the
  * idle_thread with the naked attribute.
  */
-__attribute__((naked)) NORETURN void idle_thread(void)
+void idle_thread(void)
 {
     /* We cannot use for-loop or while-loop here because they may
      * involve stack manipulations (the compiler will not allow

Is there something wrong with my toolchain?

Thanks

[HHPLow]

gcc version @lsf37

# gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 7.5.0-3ubuntu1~18.04' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-7 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)

[lsf37]

Yes, 7.5 is likely too old, you'll need at least GCC 8. Version 10 should also work.

[HHPLow]

Ok thanks~

may have another problem, seL4 doc is too old

at https://docs.sel4.systems/projects/buildsystem/host-dependencies.html
Base Build Dependencies show need Ubuntu 18.04 LTS

And Ubuntu 18.04 GCC is 7.5

Or can we add GCC version check to CMakeLists.txt to avoid such things ?
Thanks.

[lsf37]

at https://docs.sel4.systems/projects/buildsystem/host-dependencies.html
Base Build Dependencies show need Ubuntu 18.04 LTS

You're right, that is out of date and should be updated. We're in the process of updating the docker images to the current Debian stable release that came out recently, and I had the host dependency update scheduled for after that (updating to Ubuntu 20 and current Debian stable).

Or can we add GCC version check to CMakeLists.txt to avoid such things ?

That is a good idea. I'll open an issue for it.

[HHPLow]

Ok thanks for your work~