Date: Fri, 5 Sep 2014 11:43:32 -0400 From: John Baldwin <jhb@freebsd.org> To: Julian Elischer <julian@freebsd.org> Cc: freebsd-hackers@freebsd.org, kib@freebsd.org, Steven Stewart-Gallus <sstewartgallus00@mylangara.bc.ca>, Benjamin Kaduk <bjk@freebsd.org> Subject: Re: Can anyone help clarify details about the FreeBSD system call interface? Message-ID: <201409051143.33213.jhb@freebsd.org> In-Reply-To: <54090FDB.6090801@freebsd.org> References: <fb4bf68f53c5.53ff77ee@langara.bc.ca> <2041449.H6lUHcsTDl@ralph.baldwin.cx> <54090FDB.6090801@freebsd.org>
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On Thursday, September 04, 2014 9:20:27 pm Julian Elischer wrote: > 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. These system calls were NOPs in 4.4 BSD. vadvise was marked as obsolete ('ovadvise') in syscalls.master when it was first imported in 1989: http://svnweb.freebsd.org/csrg/sys/kern/syscalls.master?view=markup&pathrev=37325 I can't actually find the implementations of vadvise() and sstk() prior to the Mach VM import in the CSRG repository so I don't know how far back they were NOPs, but I doubt any FreeBSD binary uses these. -- John Baldwin
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