Date: Sat, 16 Nov 2002 19:08:05 -0800 From: Alfred Perlstein <alfred@FreeBSD.org> To: Garrett Wollman <wollman@lcs.mit.edu> Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/lib/libc/gen sysconf.c Message-ID: <20021117030805.GA6882@elvis.mu.org> In-Reply-To: <200211170202.gAH22oLd099179@khavrinen.lcs.mit.edu> References: <200211160635.gAG6ZKUX094649@repoman.freebsd.org> <200211160706.gAG76Z4S089556@khavrinen.lcs.mit.edu> <20021116095822.GT50692@elvis.mu.org> <200211170202.gAH22oLd099179@khavrinen.lcs.mit.edu>
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* Garrett Wollman <wollman@lcs.mit.edu> [021116 18:02] wrote:
> <<On Sat, 16 Nov 2002 01:58:22 -0800, Alfred Perlstein <alfred@FreeBSD.org> said:
>
> > Should I set _POSIX_AIO_MAX to 1024?
>
> You *must not* change _POSIX_AIO_MAX. Its value is fixed in the
> Standard. (Specifically, it is the minimum permissible value of
> {AIO_MAX}.)
>
> The constant AIO_MAX should probably be left undefined, thereby
> forcing applications to call sysconf(_SC_AIO_MAX) if they care -- but
> in order for this to work, sysconf() has be able to get the correct
> value of {AIO_MAX} from the kernel.
>
> Rev. 1.18 to sysconf.c is simply wrong. If the kernel is providing an
> incorrect value, it's a bug in the kernel and should not be papered
> over by the library. If AIO is not supported in the kernel, these
> values are meaningless anyway (and an error should probably be
> reported).
In re 1.18, the problem is that the code changes a 0 return to -1,
at least for _SC_AIO_PRIO_DELTA_MAX, so that portion of the revision
should stay right? (since 0 is a valid response from the kernel)
For _SC_AIO_LISTIO_MAX and _SC_AIO_MAX returning -1 when aio is not
loaded is ok, so I can revert that:
Index: gen/sysconf.c
===================================================================
RCS file: /home/ncvs/src/lib/libc/gen/sysconf.c,v
retrieving revision 1.18
diff -u -r1.18 sysconf.c
--- gen/sysconf.c 16 Nov 2002 06:35:20 -0000 1.18
+++ gen/sysconf.c 17 Nov 2002 03:06:27 -0000
@@ -254,12 +254,10 @@
return (_POSIX_TIMERS);
#endif
case _SC_AIO_LISTIO_MAX:
- defaultresult = _POSIX_AIO_LISTIO_MAX;
mib[0] = CTL_P1003_1B;
mib[1] = CTL_P1003_1B_AIO_LISTIO_MAX;
goto yesno;
case _SC_AIO_MAX:
- defaultresult = _POSIX_AIO_MAX;
mib[0] = CTL_P1003_1B;
mib[1] = CTL_P1003_1B_AIO_MAX;
goto yesno;
--
-Alfred Perlstein [alfred@freebsd.org]
'Instead of asking why a piece of software is using "1970s technology,"
start asking why software is ignoring 30 years of accumulated wisdom.'
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