Hi Elliott! On Tue, Mar 26, 2024 at 03:27:27PM -0700, enh wrote: > i'm not sure a lot of the text in getpagesize.2 is very helpful? for > example: > > Portable applications should employ sysconf(_SC_PAGESIZE) instead > of getpagesize(): > > #include <unistd.h> > long sz = sysconf(_SC_PAGESIZE); > > (Most systems allow the synonym _SC_PAGE_SIZE for _SC_PAGESIZE.) > > is this a good recommendation _unless_ you've found yourself on a system > that doesn't have getpagesize()? on Android i'm advising getpagesize() > because it's (a) attribute const and (b) inherently cheaper than sysconf(). > (though obviously, "if it really matters, stick it in a static".) > > afaict the only motivation for the "portable applications" advice is that > HP-UX removed getpagesize() at some point? but given that HP-UX has been > kept "alive" in an artificial coma since 2007... does anyone writing code > in 2024 need to worry about that enough for this to be good advice? I hope not. It's dead, AFAIC. > getpagesize() is available on Android, *BSD, iOS/macOS, glibc/musl, and > even mingw! > > Whether getpagesize() is present as a Linux system call depends > on the architecture. If it is, it returns the kernel symbol > PAGE_SIZE, whose value depends on the architecture and machine > model. Generally, one uses binaries that are dependent on the > architecture but not on the machine model, in order to have a > single binary distribution per architecture. This means that a > user program should not find PAGE_SIZE at compile time from a > header file, but use an actual system call, at least for those > architectures (like sun4) where this dependency exists. > > should this just say alpha, sparc32, and sparc64 instead of being vague? (i Yep, I'd appreciate that, after the current text (not replacing it). > suspect anyone who doesn't default to searching the kernel source would > turn to the man pages to answer the "which architectures?" question :-) > though i'm not sure why anyone who doesn't read the kernel source would > care whether getpagesize() should really be in man2 or man3...) > > glibc 2.0 fails because its getpagesize() returns a statically > derived value, and does not use a system call. Things are OK in > glibc 2.1. > > 1997 called, and wondered whether we're helping anyone by documenting a bug > that's been fixed longer than several folks on my team have been alive? :-) Agree. Do you intend to send patches? Otherwise, let me know, and I'll prepare something. Have a lovely night! Alex -- <https://www.alejandro-colomar.es/> Looking for a remote C programming job at the moment.
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