Hello All,
>>>> All instances have been replaced by empty functions with an alias. e.g.
>>>> void __do_something (args) {}
>>>> do_something(args) __atttribute__((weak, alias("__do_something")));
> Good to know. This doc also helps:
> http://docs.sun.com/app/docs/doc/817-1984/chapter2-11?l=en&a=view
> Then,
> - we must try to not leave undefined weak symbols at all,
> - or check the symbol before invocation for the safety in case of NULL
> dereference.
My 2 cents:
And here an example from the linux kernel that just does the first option:
Create a default fallback routine that can be used if there is no
strong implementation:
-------------------------------------------------------------------------------------------
__attribute__((weak)) unsigned long long printk_clock(void)
{
return sched_clock();
}
-------------------------------------------------------------------------------------------
and here is an example of the strong implementation (from the ARM architecture):
-------------------------------------------------------------------------------------------
unsigned long long printk_clock(void)
{
return (unsigned long long)(jiffies - INITIAL_JIFFIES) *
(1000000000 / HZ);
}
-------------------------------------------------------------------------------------------
If the strong implementation is available, the weak is simply
discarded during linking, if the strong is omitted, the weak is used
as fallback. This is a clean, lean and mean example without
complex/superfluous aliases or checks for NULL pointers.
It should not get any harder than this...
Kind Regards,
Remy
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