On Fri, Aug 4, 2017 at 9:20 AM, Tom Rini <tr...@konsulko.com> wrote: > On Thu, Aug 03, 2017 at 06:27:02AM +0200, Heinrich Schuchardt wrote: >> Hello Tom, >> >> for the UEFI implementation of U-Boot it would make defining string >> constants much easier using the following C 2011 notation: >> >> u16 *foo = u"My lovely string"; >> >> Do you see any reason forcing us not to use features of C 2011? >> >> In /Makefile I found the following: >> >> ifeq ($(HOSTOS),cygwin) >> HOSTCFLAGS += -ansi >> endif >> >> # >> # Xtensa linker script cannot be preprocessed with -ansi because of >> # preprocessor operations on strings that don't make C identifiers. >> # >> ifeq ($(CONFIG_XTENSA),) >> LDPPFLAGS += -ansi >> endif >> >> # Create a file containing the configuration options the image was built >> with >> quiet_cmd_cpp_cfg = CFG $@ >> cmd_cpp_cfg = $(CPP) -Wp,-MD,$(depfile) $(cpp_flags) $(LDPPFLAGS) -ansi \ >> -DDO_DEPS_ONLY -D__ASSEMBLY__ -x assembler-with-cpp -P -dM -E -o $@ $< >> >> The GCC documentation teaches: >> -ansi: In C mode, this is equivalent to -std=c90. In C++ mode, it is >> equivalent to -std=c++98. >> >> When I am building for arm64 I find these options actually used: >> >> aarch64-linux-gnu-gcc -Wp,-MD,common/.cli_hush.o.d -nostdinc -isystem >> /usr/lib/gcc-cross/aarch64-linux-gnu/6/include -Iinclude >> -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__ >> -D__UBOOT__ -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin >> -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks >> -g -fstack-usage -Wno-format-nonliteral -Werror=date-time -D__ARM__ >> -fno-pic -mstrict-align -ffunction-sections -fdata-sections -fno-common >> -ffixed-r9 -fno-common -ffixed-x18 -pipe -march=armv8-a >> -D__LINUX_ARM_ARCH__=8 -I./arch/arm/mach-meson/include >> -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(cli_hush)" >> -D"KBUILD_MODNAME=KBUILD_STR(cli_hush)" -c -o common/cli_hush.o >> common/cli_hush.c >> >> My impression is that: >> >> We have variables in /Makefile that are not used for anything: >> LDPPFLAGS, cmd_cpp_cfg, cmd_cpp_lds. >> >> All lines refering to these variables should be removed. >> Cf. https://lists.denx.de/pipermail/u-boot/2016-September/267177.html > > OK. Drop 'em, throw travis-ci at it and see what, if anything, blows > up. > >> We force C90 on cygwin to compile the host code but not for the actual >> U-Boot code. Probably a remnant from a distant past. >> >> So nothing should stop us from using C2011 in U-Boot. > > What's the minimum gcc (and llvm) version we need to use here? Thanks! >
It looks like probably gcc 4.9[1].. maybe 4.7 or even v4.6[2] is complete enough for what we need.. that seems plenty old enough. I'm less familiar with clang but wikipedia says 3.1[2]. If some board/arch was stuck on something older, I guess we could make it a kconfig option that EFI_LOADER depends on. [1] https://gcc.gnu.org/wiki/C11Status [2] https://en.wikipedia.org/wiki/C11_(C_standard_revision) BR, -R _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
