----- Am 13. Sep 2018 um 14:07 schrieb joel j...@rtems.org:
> On Thu, Sep 13, 2018, 3:28 AM Sebastian Huber <
> sebastian.hu...@embedded-brains.de> wrote:
>
>> Hello,
>>
>> I test currently the tqm8xx BSP which worked fine until RTEMS 5. The
>> problem is that this BSP uses strtoul() to get some system configuration
>> parameters from the boot loader. The Newlib used by RTEMS 5 has now
>> support for C locales in strtoul(). The C locale support needs an
>> executing thread with a valid Newlib reentrancy structure. This is
>> definitely not the case during bsp_start().
>>
>
> Why do we now longer have a global reentrancy structure to fall back on?
I think having a global reentrancy as a fall back just for the lowest level
system start without an idle thread is a bit of overkill.
The heavy weight C local support which was recently introduced in Newlib is not
really the right thing for the embedded systems I know. There were several
complaints about this on the Newlib mailing list as well. The root cause for
this is the C standard. So, basically the C standard strtoul() is unsuitable
for embedded systems. The FreeBSD (sys/kern/strtoul.c) and Linux
(lib/kstrtox.c) kernel have their own implementations.
>
> If you disable newlib reentrancy via confdefs.h, what happens?
This configuration option is not really great. It results in
#if defined(RTEMS_NEWLIB)
struct _reent *__getreent(void)
{
#ifdef CONFIGURE_DISABLE_NEWLIB_REENTRANCY
return _GLOBAL_REENT;
#else
return _Thread_Get_executing()->libc_reent;
#endif
}
#endif
Since the configuration object is normally directly presented to the linker, we
have a reference to _global_impure_ptr which is a heavy weight object. For low
end targets, we need something better.
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