_ioperm support for Arm

[Adhemerval Zanella]

On 29/05/2019 11:57, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>> Also, from previous Cauldron discussion, we should make the deprecation
>> in longer phases.  It also seems that compiler warning that symbol will
>> be deprecated in future releases is not a complete way to warn developers
>> to add configure build options take this consideration (the libgo example
>> with uname come to my mind). So maybe we use a different strategy for
>> sysctl, by deprecating in 2/3 releases and make it a compat symbol after
>> 3/4 releases.
> 
> I think the ustat business was due to the fact that we did *not* issue a
> warning beforehand.  Like sysctl, the deprecation is mainly captured in
> the manual page for the system call.

Right, this was raised on Cauldron as well. GCC developers also asked to
extend the deprecation phase a bit longer if I recall correctly.

> 
> The linker warnings happen only on some architectures right now (which
> use the “generic” Linux system call ABI).

This is standard ENOSYS stub we emit for non-implemented symbols. I think
we will need both add __attribute_deprecated__ and create a new stub with
a different warning message (maybe "symbol is deprecated and it will be 
removed in future versions").

> 
> Once we've settled the ioperm matter for Arm, I will try to come up with
> a simple patch that adds deprecation warnings for sysctl.
>