Can anyone help clarify details about the FreeBSD system call interface?

[Julian Elischer]

On 9/4/14, 7:06 AM, John Baldwin wrote:
> On Wednesday, September 03, 2014 05:30:01 PM Benjamin Kaduk wrote:
>> On Thu, 28 Aug 2014, Steven Stewart-Gallus wrote:
>>>> svn blame says that the whole implementation dates from r1541.
>>>> Looks like
>>>> it was never implemented.  Some googling indicates that it was a
>>>> plannedroutine to set the stack size, which was never implemented,
>>>> anywhere.
>>>>
>>>> The locking comments were added in r79224, but the implementation is
>>>> otherwise from r1541, i.e., it was never implemented.
>>> Alright, so sys/kern/syscalls.master can be patched somewhat like so
>>> and I won't need to document them?
>>>
>>> -72	AUE_O_VADVISE	STD	{ int ovadvise(int anom); } vadvise \
>>> -				    ovadvise_args int
>>> +72	AUE_NULL	OBSOL   ovadvise
>>>
>>> -70	AUE_SSTK	STD	{ int sstk(int incr); }
>>> +70	AUE_SSTK	OBSOL	sstk
>> I don't think so; I think that would be a regression.
>>
>> We do currently provide implementations for these syscalls, that just
>> happen to always return failure.  I think that the OBSOL annotation
>> corresponds to a complete lack of implementation.  Perhaps it would be
>> acceptable at a major release boundary, but this is not my area of
>> expertise.
> For these two calls, I doubt anything is actually using them.  They've been
> stubs since the Mach VM was imported into BSD in 1990.  We don't ship a system
> call for creat() anymore either.  In this particular case, I think it would be
> more of a feature if those symbols disappeared from libc and caused link
> errors.
have we ever shipped code for creat?

if we lose teh ability to run FreeBSD 1.1 chroots I'll be most upset.. 
it's a great
selling point when pointing out  our commitment to ABI stability and 
backwards
portability.