[uml-user] 3.16 build without optimization fails

[Thomas M. <th...@m3...>]

Hi,

the build with -O0 fails with:

make -f scripts/Makefile.build obj=init
  gcc -Wp,-MD,init/.main.o.d  -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.8.3/include -I./arch/um/include -Iarch/um/include/generated  -Iinclude -I./arch/um/include/uapi -Iarch/um/include/generated/uapi -I./include/uapi -Iinclude/generated/uapi -include ./include/linux/kconfig.h -D__KERNEL__ -m64 -I./arch/x86/um -I./arch/x86/include -I./arch/x86/include/uapi -Iarch/x86/include/generated -Iarch/x86/include/generated/uapi -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Wno-format-security -mcmodel=large -fno-builtin -m64 -funit-at-a-time -D__arch_um__ -I./arch/um/include/shared -I./arch/x86/um/shared -I./arch/um/include/shared/skas -Dvmap=kernel_vmap -Din6addr_loopback=kernel_in6addr_loopback -Din6addr_any=kernel_in6addr_any -Dstrrchr=kernel_strrchr -D_LARGEFILE64_SOURCE -Derrno=kernel_errno -Dsigprocmask=kernel_sigprocmask -Dmktime=kernel_mktime -fno-delete-null-pointer-checks -O0 -Wframe-larger-than=1024 -fno-stack-protector -Wno-unused-but-set-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -fno-var-tracking-assignments -g -Wdeclaration-after-statement -Wno-pointer-sign -fno-strict-overflow -fconserve-stack -Werror=implicit-int -Werror=strict-prototypes -DCC_HAVE_ASM_GOTO    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(main)"  -D"KBUILD_MODNAME=KBUILD_STR(main)" -c -o init/main.o init/main.c
In file included from ./arch/um/include/asm/fixmap.h:58:0,
                 from ./arch/um/include/asm/pgtable.h:11,
                 from include/linux/mm.h:51,
                 from include/linux/ring_buffer.h:5,
                 from include/linux/ftrace_event.h:5,
                 from include/trace/syscall.h:6,
                 from include/linux/syscalls.h:80,
                 from init/main.c:18:
include/asm-generic/fixmap.h: In function 'fix_to_virt':
include/asm-generic/fixmap.h:31:2: error: size of unnamed array is negative
  BUILD_BUG_ON(idx >= __end_of_fixed_addresses);
  ^
make[1]: *** [init/main.o] Error 1
make: *** [init] Error 2

bug or feature?

any ideas?

switching BUILD_BUG_ON unconditionally to BUILD_BUG_ON_MSG - which uses compiletime_assert() - breaks the build a bit later here:

  gcc -Wp,-MD,arch/um/kernel/skas/.uaccess.o.d  -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.8.3/include -I./arch/um/include -Iarch/um/include/generated  -Iinclude -I./arch/um/include/uapi -Iarch/um/include/generated/uapi -I./include/uapi -Iinclude/generated/uapi -include ./include/linux/kconfig.h -D__KERNEL__ -m64 -I./arch/x86/um -I./arch/x86/include -I./arch/x86/include/uapi -Iarch/x86/include/generated -Iarch/x86/include/generated/uapi -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Wno-format-security -mcmodel=large -fno-builtin -m64 -funit-at-a-time -D__arch_um__ -I./arch/um/include/shared -I./arch/x86/um/shared -I./arch/um/include/shared/skas -Dvmap=kernel_vmap -Din6addr_loopback=kernel_in6addr_loopback -Din6addr_any=kernel_in6addr_any -Dstrrchr=kernel_strrchr -D_LARGEFILE64_SOURCE -Derrno=kernel_errno -Dsigprocmask=kernel_sigprocmask -Dmktime=kernel_mktime -fno-delete-null-pointer-checks -O0 -Wframe-larger-than=1024 -fno-stack-protector -Wno-unused-but-set-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -fno-var-tracking-assignments -g -Wdeclaration-after-statement -Wno-pointer-sign -fno-strict-overflow -fconserve-stack -Werror=implicit-int -Werror=strict-prototypes -DCC_HAVE_ASM_GOTO    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(uaccess)"  -D"KBUILD_MODNAME=KBUILD_STR(uaccess)" -c -o arch/um/kernel/skas/uaccess.o arch/um/kernel/skas/uaccess.c
In file included from include/linux/err.h:4:0,
                 from arch/um/kernel/skas/uaccess.c:6:
arch/um/kernel/skas/uaccess.c: In function 'do_op_one_page':
include/linux/compiler.h:346:20: error: call to '__compiletime_assert_85' declared with attribute error: BUILD_BUG_ON failed: __same_type(((void *)addr), struct page *)
    prefix ## suffix();    \
                    ^
include/linux/compiler.h:351:2: note: in expansion of macro '__compiletime_assert'
  __compiletime_assert(condition, msg, prefix, suffix)
  ^
include/linux/compiler.h:363:2: note: in expansion of macro '_compiletime_assert'
  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
  ^
include/linux/bug.h:50:37: note: in expansion of macro 'compiletime_assert'
 #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                     ^
include/linux/bug.h:74:1: note: in expansion of macro 'BUILD_BUG_ON_MSG'
 BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
 ^
include/linux/highmem.h:125:2: note: in expansion of macro 'BUILD_BUG_ON'
  BUILD_BUG_ON(__same_type((addr), struct page *));       \
  ^
arch/um/kernel/skas/uaccess.c:85:2: note: in expansion of macro 'kunmap_atomic'
  kunmap_atomic((void *)addr);
  ^
make[2]: *** [arch/um/kernel/skas/uaccess.o] Error 1
make[1]: *** [arch/um/kernel/skas] Error 2
make: *** [arch/um/kernel] Error 2