Build 找不到 Stdio.h 但我可以...？

Question

I have #include <stdio.h> (no extra spaces) and locate stdio.h shows a few viable options. And yet, when I build, it always says it can't be found. I can include it with a full path #include "/usr/include/stdio.h" , but then its own dependencies (features.h) can't be found. I tried specifically sourcing the /usr/include folder which I imagine should already be good to go anyway, but that doesn't help it find it either. So... what the heck? I'm also building with sudo privileges. I can't fathom a good reason for it to not be found.

output from make V=1 VERBOSE=1

******************** Release Build **********************
make -C /lib/modules/4.15.0-58-generic/build SUBDIRS=/home/username/project modules 
make[1]: Entering directory '/usr/src/linux-headers-4.15.0-58-generic'
test -e include/generated/autoconf.h -a -e include/config/auto.conf || (        \
echo >&2;                           \
echo >&2 "  ERROR: Kernel configuration is invalid.";       \
echo >&2 "         include/generated/autoconf.h or include/config/auto.conf are missing.";\
echo >&2 "         Run 'make oldconfig && make prepare' on kernel src to fix it.";  \
echo >&2 ;                          \
/bin/false)
mkdir -p /home/username/project/.tmp_versions ; rm -f /home/username/project/.tmp_versions/*                                        */
make -f ./scripts/Makefile.build obj=/home/username/project
******************** Release Build **********************
  gcc -Wp,-MD,/home/username/project/.file_main.o.d  -nostdinc -isystem /usr/lib/gcc/x86_64-linux-gnu/5/include  -I./arch/x86/include -I./arch/x86/include/generated  -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -Iubuntu/include  -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -Werror-implicit-function-declaration -Wno-format-security -std=gnu89 -fno-PIE -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -falign-jumps=1 -falign-loops=1 -mno-80387 -mno-fp-ret-in-387 -mpreferred-stack-boundary=3 -mskip-rax-setup -mtune=generic -mno-red-zone -mcmodel=kernel -funit-at-a-time -DCONFIG_X86_X32_ABI -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 -DCONFIG_AS_FXSAVEQ=1 -DCONFIG_AS_SSSE3=1 -DCONFIG_AS_CRC32=1 -DCONFIG_AS_AVX=1 -DCONFIG_AS_AVX2=1 -DCONFIG_AS_AVX512=1 -DCONFIG_AS_SHA1_NI=1 -DCONFIG_AS_SHA256_NI=1 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -mindirect-branch=thunk-extern -mindirect-branch-register -fno-delete-null-pointer-checks -O2 --param=allow-store-data-races=0 -DCC_HAVE_ASM_GOTO -Wframe-larger-than=1024 -fstack-protector-strong -Wno-unused-but-set-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -fno-var-tracking-assignments -pg -mfentry -DCC_USING_FENTRY -Wdeclaration-after-statement -Wno-pointer-sign -fno-strict-overflow -fno-merge-all-constants -fmerge-constants -fno-stack-check -fconserve-stack -Werror=implicit-int -Werror=strict-prototypes -Werror=date-time -Werror=incompatible-pointer-types -Werror=designated-init -DCHARACTER_DRIVER -DCUSTOM_LOGIC -DOEM_001_CUSTOM_LOGIC -DNO_STATS_DEBUG  -DMODULE  -DKBUILD_BASENAME='"file_main"'  -DKBUILD_MODNAME='"file"' -c -o /home/username/project/file_main.o /home/username/project/file_main.c
In file included from /home/username/project/file_main.c:13:0:
/home/username/project/file.h:10:19: fatal error: stdio.h: No such file or directory
compilation terminated.

Answer 1

You need to use printk , not printf . Its definition is in linux/printk.h , not stdio.h .

Please include these details in your question the next time you ask.

The reason your build is not able to find stdio.h is because it's not available in the kernel sources, and you're compiling with -nostdinc . -nostdinc causes all the default search paths to be ignored.