[LLVMdev] Customize Standard C Library Using LLVM (to support llvm backend optimization)

[Chao Yan]

2015-03-11 16:22 GMT-05:00 Richard Gorton <
rcgorton at cognitive-electronics.com>:

> I can confirm that musl builds and works correctly with clang/llvm.  We
> are using musl as a libc for our architecture.
> It has a much smaller code footprint than newlib or glibc.
>


I successfully cross-compile the must-libc using clang, with the
configuration:

C=clang CFLAGS=--target=arm-none-linux-gnueabi\
--sysroot=/usr/local/arm-2009q\ -I\
/usr/local/arm-2009q3/arm-none-linux-gnueabi/libc/usr/include/ LIBCC=
./configure --target=arm

But how to force clang  to use musl-libc rather than its default one? I
tried

clang --target arm-none-linux-gnueabi -nostdlib -static hello.c
~/research/musl-1.1.6/lib/crt1.o ~/research/musl-1.1.6/lib/crti.o
~/research/musl-1.1.6/lib/crtn.o -I ~/research/musl-1.1.6/include/ -L
~/research/musl-1.1.6/lib/ -L
/usr/local/arm-2009q3/lib/gcc/arm-none-linux-gnueabi/4.4.1/ -lc -lgcc
-lgcc_eh

clang complaint:

/usr/local/arm-2009q3/bin/arm-none-linux-gnueabi-ld: warning: library
search path "/lib/../lib" is unsafe for cross-compilation
/usr/local/arm-2009q3/bin/arm-none-linux-gnueabi-ld: warning: library
search path "/usr/lib/../lib" is unsafe for cross-compilation
/usr/local/arm-2009q3/bin/arm-none-linux-gnueabi-ld: warning: library
search path "/lib" is unsafe for cross-compilation
/usr/local/arm-2009q3/bin/arm-none-linux-gnueabi-ld: warning: library
search path "/usr/lib" is unsafe for cross-compilation
/home/yanchao/research/musl-1.1.6/lib//libc.a(__libc_start_main.o): In
function `__libc_start_main':
src/env/__libc_start_main.c:(.text+0x30): undefined reference to
`__aeabi_memset'
/home/yanchao/research/musl-1.1.6/lib//libc.a(vfprintf.o): In function
`vfprintf':
src/stdio/vfprintf.c:(.text+0x28): undefined reference to `__aeabi_memset'
/usr/local/arm-2009q3/lib/gcc/arm-none-linux-gnueabi/4.4.1//libgcc.a(_dvmd_lnx.o):
In function `__aeabi_ldiv0':
(.text+0x8): undefined reference to `raise'
/usr/local/arm-2009q3/lib/gcc/arm-none-linux-gnueabi/4.4.1//libgcc_eh.a(unwind-arm.o):
In function `unwind_phase2':
unwind-arm.c:(.text+0xae4): undefined reference to `abort'
/usr/local/arm-2009q3/lib/gcc/arm-none-linux-gnueabi/4.4.1//libgcc_eh.a(unwind-arm.o):
In function `__gnu_Unwind_Resume':
unwind-arm.c:(.text+0xbe8): undefined reference to `abort'
unwind-arm.c:(.text+0xc10): undefined reference to `abort'
/usr/local/arm-2009q3/lib/gcc/arm-none-linux-gnueabi/4.4.1//libgcc_eh.a(pr-support.o):
In function `_Unwind_GetTextRelBase':
pr-support.c:(.text+0x4): undefined reference to `abort'
/usr/local/arm-2009q3/lib/gcc/arm-none-linux-gnueabi/4.4.1//libgcc_eh.a(pr-support.o):
In function `_Unwind_GetDataRelBase':
pr-support.c:(.text+0xc): undefined reference to `abort'

Regards,
Chao
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