support for calling Linux syscalls directly

[David Miller]

From: Rich Felker <dalias@aerifal.cx>
Date: Tue, 12 Feb 2013 13:04:01 -0500

> On Tue, Feb 12, 2013 at 12:52:52PM -0500, David Miller wrote:
>> From: chrubis@suse.cz
>> Date: Tue, 12 Feb 2013 18:46:38 +0100
>> 
>> > I do the LTP[1] which makes legitimate use of syscall(3) as for the
>> > testing purposes we need to be able to call bare syscalls in order to
>> > validate both glibc and kernel API. And removing the call would mess
>> > backward compatibility.
>> 
>> I don't think it makes sense for every source tree that wants to
>> call syscall directly to have to duplicate over and over again the
>> argument passing quirks of various architectures.
>> 
>> Multiple instances of such tricky code means multiple places for
>> the same bugs over and over again.
> 
> LTP is a very special case. It's a test suite for the kernel API/ABI,
> so of course it needs to be aware of (and testing!) these differences
> to make sure nobody breaks them (which would in turn break glibc).

And everyone who wanted to write such a testsuite as well would have
the same needs, and duplicate.