Date: Tue, 1 Nov 2011 10:47:32 -0700 From: Peter Wemm <peter@wemm.org> To: Ed Schouten <ed@80386.nl> Cc: arch@freebsd.org, Jilles Tjoelker <jilles@stack.nl> Subject: Re: [PATCH] fadvise(2) system call Message-ID: <CAGE5yCoM5jHs3eyi-AUBikOMy3gBR2yz%2BkqnRC_ipNO-j51EKw@mail.gmail.com> In-Reply-To: <20111101141937.GV2258@hoeg.nl> References: <201110281426.00013.jhb@freebsd.org> <201110311717.53476.jhb@freebsd.org> <20111031221627.GR2258@hoeg.nl> <201111011001.42775.jhb@freebsd.org> <20111101141937.GV2258@hoeg.nl>
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On Tue, Nov 1, 2011 at 7:19 AM, Ed Schouten <ed@80386.nl> wrote: > Hi John, > > * John Baldwin <jhb@freebsd.org>, 20111101 15:01: >> Hmmm, there is an fadvise(2) manpage. =A0I had presumed from that it was >> a public interface. > > That's interesting. What kind of distro/version are you using? I'm using > libc6-2.13-20ubuntu5 from Ubuntu 11.10 (amd64). Don't forget that the Linux kernel syscalls are not automatically published to userland like ours are. glibc is (usually) very deliberate about what symbols it publishes, what macros it defines in its #include mess, and so on. Just because a syscall is called "fadvise" in the kernel doesn't mean the userland part is fadvise as well, if it even exists. Heck, even glibc might not assume the syscall exists in the kernel. eg: mrename() and so on. eg: lseek vs llseek and all the syscall64 variants. Bottom line(s): 1) Is this a standardized symbol? 2) Is it used in other OS's? 3) Do the implementations vary? If it exists in a widely used linux, it counts a lot as a "defacto" standardized defintion. Also, does autoconf/automake have stubs to check for it? and so on. --=20 Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI6FJV "All of this is for nothing if we don't go to the stars" - JMS/B5 "If Java had true garbage collection, most programs would delete themselves upon execution." -- Robert Sewell
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