Date: Wed, 23 Oct 2002 14:14:03 -0400 (EDT) From: Garrett Wollman <wollman@lcs.mit.edu> To: Craig Rodrigues <rodrigc@attbi.com> Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/lib/libc/sys aio_cancel.2 aio_error.2 aio_read.2 aio_return.2 aio_suspend.2 aio_waitcomplete.2 aio_write.2 Message-ID: <200210231814.g9NIE3to097645@khavrinen.lcs.mit.edu> In-Reply-To: <20021023110619.A27272@attbi.com> References: <200210221612.g9MGCR1p012070@repoman.freebsd.org> <20021022161820.GA57732@starjuice.net> <20021022164649.GS91539@elvis.mu.org> <20021022132829.A22126@attbi.com> <xzpd6q1poco.fsf@flood.ping.uio.no> <20021023110619.A27272@attbi.com>
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<<On Wed, 23 Oct 2002 11:06:19 -0400, Craig Rodrigues <rodrigc@attbi.com> said: > +.Sh KERNEL OPTIONS [...] .Sh APPLICATION USAGE Asynchronous I/O is specified as an option in .St -p1003.1-2001 and earlier standards. A portable application must be prepared for the possibility that asynchronous I/O may not be available, and also that it may not be available at run-time for certain files or types of file descriptors. .Pp The .Dv _POSIX_ASYNCHRONOUS_IO macro in .In unistd.h describes the compile-time support for .Nm . The following conditions are possible: .Bl -inset -offset indent .It Dv _POSIX_ASYNCHRONOUS_IO No is not defined . The implementation provides no information about whether programs using .Nm can be compiled. .It Dv _POSIX_ASYNCHRONOUS_IO No is defined to \-1 . The implementation does not support the asynchronous I/O feature; the .In aio.h header file and .Fn aio_* functions are not provided. .It Dv _POSIX_ASYNCHRONOUS_IO No is defined to a positive integer . The implementation supports the asynchronous I/O feature unconditionally, for all files and all file descriptors. The .In aio.h header file and .Fn aio_* functions are provided. .It Dv _POSIX_ASYNCHRONOUS_IO No is defined to zero . The implementation optionally supports asynchronous I/O. The .In aio.h header file and .Fn aio_* functions are provided. However, the result of calling any .Fn aio_* function is undefined unless the application has checked that the asynchronous I/O option is supported on the files or file descriptors it plans to use, by calling the .Xr pathconf 2 or .Xr fpathconf 2 function with a .Fa name argument of .Dv _PC_ASYNC_IO . If .Nm is available for the specified file (or descriptor), .Xr pathconf 2 (or .Xr fpathconf 2 ) will return a positive integer which is equal to the value specified for .Dv _POSIX_VERSION by the version of the standard the system implements. .El .Pp These configuration parameters can be queried by shell scripts using the .Xr getconf 1 program. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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