Hi Marek,
On Sun, Mar 7, 2021 at 12:26 PM 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. memset() can be generated sometimes as well.
This then results in the following linking error: .../lz4.c:93: undefined reference to `memcpy' .../uuid.c:206: more undefined references to `memcpy' follow
Make memcpy() and memset() visible by using the __used macro to avoid this error.
This sounds like a GCC bug of using -fno-builtin and -flto. Could you file a bugzilla to GCC people to get some comments?
Signed-off-by: Marek Behún marek.behun@nic.cz
lib/string.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
Regards, Bin