[PATCH] Revert "time: add weak annotation to timer_read_counter declaration"

Harald Seiler hws at denx.de
Thu Jan 5 01:08:47 CET 2023

This reverts commit 65ba7add0d609bbd035b8d42fafdaf428ac24751.

A weak extern is a nasty sight to behold: If the symbol is never
defined, on ARM, the linker will replace the function call with a NOP.
This behavior isn't well documented but there are at least some hints
to it [1].

When timer_read_counter() is not defined, this obviously does the wrong
thing here and it does so silently.  The consequence is that a board
without timer_read_counter() will sleep for random amounts and generally
have erratic get_ticks() values.

Drop the __weak annotation of the extern so a linker error is raised
when timer_read_counter() is not defined.  This is okay, the original
reason for the reverted change - breaking the sandbox build - no longer

Final sidenote:  This was the only weak extern in the entire tree at
this time as far as I can tell.  I guess we should avoid introduction of
them again as they are obviously a very big footgun.

[1]: https://stackoverflow.com/questions/31203402/gcc-behavior-for-unresolved-weak-functions

Fixes: 65ba7add0d60 ("time: add weak annotation to timer_read_counter declaration")
Reported-by: Serge Bazanski <q3k at q3k.org>
Signed-off-by: Harald Seiler <hws at denx.de>
 lib/time.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/time.c b/lib/time.c
index f3aaf472d1..1e24b1b03c 100644
--- a/lib/time.c
+++ b/lib/time.c
@@ -63,7 +63,7 @@ ulong timer_get_boot_us(void)
-extern unsigned long __weak timer_read_counter(void);
+extern unsigned long timer_read_counter(void);

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