Re: [patch] New option --disable-reenterable-atexit

[Sebastian Huber <sebastian dot huber at embedded-brains dot de>]

On 2013-10-16 08:39, Joey Ye wrote:
> There is an existing macro to declare atexit data structure as global
> variables, so that it can be discarded if not used to save memory
> consumption. But this macro was only enabled for certain targets.
>
> This patch adds an configure option --disable-reenterable-atexit for more
> targets.
>
> ChangeLog:
> 2013-10-16  Joey Ye<joey.ye@arm.com>
>
> 	configure.in (disable-reenterable-atexit): New option.
> 	configure: Regenerated.
> 	newlib.hin (_REENT_GLOBAL_ATEXIT): Place-holder.
> 	README (disable-reenterable-atexit): Description for
> 	new option.
>
>
> reent_atexit-1010.patch
>
>
> diff --git a/newlib/README b/newlib/README
> index a8aba99..9b2d5b0 100644
> --- a/newlib/README
> +++ b/newlib/README
> @@ -288,6 +288,12 @@ One feature can be enabled by specifying `--enable-FEATURE=yes' or
>        Disable dynamic allocation of atexit entries.
>        Most hosts and targets have it enabled in configure.host.
>
> +`--disable-reenterable-atexit'
> +     Disable reenterablility of atexit by declare related data structures
> +     as global variables. By doing these data structures can be discarded
> +     if atexit is not referenced.
> +     Enabled by default.

I think the naming and the description is a bit misleading.  The atexit() 
support is not thread specific.  Operations are serialized with the 
__atexit_lock lock.  In case _REENT_GLOBAL_ATEXIT is undefined, then the data 
structures for the atexit() support are part of struct _reent, but only used in 
_GLOBAL_REENT.  Thus the space in the thread specific structures is wasted. 
See also

https://sourceware.org/ml/newlib/2013/msg00355.html

--
Sebastian Huber, embedded brains GmbH

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