On Thu, 20 May 2021 at 05:25, Marek Behún marek.behun@nic.cz wrote:
It seems that sometimes (happening on ARM64, for example with turris_mox_defconfig) GCC, when linking with LTO, changes the symbol names of some functions, for example lib/string.c's memcpy() function to memcpy.isra.0.
This is a problem however when GCC for a code such as this: struct some_struct *info = get_some_struct(); struct some struct tmpinfo; tmpinfo = *info; emits a call to memcpy() by builtin behaviour, to copy *info to tmpinfo.
This then results in the following linking error: .../lz4.c:93: undefined reference to `memcpy' .../uuid.c:206: more undefined references to `memcpy' follow
GCC's documentation says this about -nodefaultlibs option: The compiler may generate calls to "memcmp", "memset", "memcpy" and "memmove". These entries are usually resolved by entries in libc. These entry points should be supplied through some other mechanism when this option is specified.
Make these functions visible by using the __used macro to avoid this error.
Signed-off-by: Marek Behún marek.behun@nic.cz
lib/string.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
Reviewed-by: Simon Glass sjg@chromium.org