Kernel-space ctypes.h support?

[Joel Sherrill]

On Thu, Sep 13, 2018, 9:25 PM Chris Johns <chrisj at rtems.org> wrote:

> On 14/09/2018 10:13, Joel Sherrill wrote:
> > On Thu, Sep 13, 2018, 5:40 PM Chris Johns <chrisj at rtems.org
> > <mailto:chrisj at rtems.org>> wrote:
> >     On 14/09/2018 02:30, Joel Sherrill wrote:
> >     > On Thu, Sep 13, 2018, 10:34 AM Sebastian Huber
> >     > <sebastian.huber at embedded-brains.de
> >     <mailto:sebastian.huber at embedded-brains.de>
> >     <mailto:sebastian.huber at embedded-brains.de
> >     <mailto:sebastian.huber at embedded-brains.de>>>
> >     > wrote:
> >     >     ----- Am 13. Sep 2018 um 14:07 schrieb joel joel at rtems.org
> >     <mailto:joel at rtems.org>
> >     >     <mailto:joel at rtems.org <mailto:joel at rtems.org>>:
> >     >
> >     >     > On Thu, Sep 13, 2018, 3:28 AM Sebastian Huber <
> >     >     > sebastian.huber at embedded-brains.de
> >     <mailto:sebastian.huber at embedded-brains.de>
> >     >     <mailto:sebastian.huber at embedded-brains.de
> >     <mailto:sebastian.huber at 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.
> >     >
> >     >
> >     > FWIW the FACE Technical Standard does not include wide characters
> in ANY
> >     profile
> >     > as of Edition 3.0. None of the RTOS vendors knew of any avionics
> users. It
> >     > wasn't viewed as a necessary feature. We could consider disabling
> it by
> >     default.
> >     >
> >
> >     Is this something we could ot would want to control with newlib via
> a config
> >     option?
> >
> >
> > We don't turn on locale for h8, m32c and maybe not epiphany. I am pretty
> sure.it
> > <http://sure.it> is an option. And should be a documented RSB option to
> turn it
> > back on. Should be a size savings for most users.
>
> We turn on or off as an option?
>

Based on Sebastian's observation, I think off.

Does this impact wide characters and multibyte?

We will need to document the impact. I suspect it removes some POSIX
support in a base build.

>
> Chris
>
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