On Tue, Aug 29, 2017 at 8:32 AM, enh <[email protected]> wrote: > can't you just infer musl from the relatively small
...number of c libraries out there... > ? > > #if defined(__linux__) && (!defined(__BIONIC__) && !defined(__GLIBC__) > && whatever ulibc is if you haven't given up on that yet) > #define __MUSL__ > #endif > > ? > > On Mon, Aug 28, 2017 at 10:35 PM, Rob Landley <[email protected]> wrote: >> The point of chrt is to use the sched_setscheduler() syscall to change a >> PID's scheduler category (by default making it a realtime process), but >> the musl-libc maintainer decided he didn't like that system call and >> changed the wrapper to return -ENOSYS instead of making the system call: >> >> https://git.musl-libc.org/cgit/musl/commit?id=1e21e78bf7a5c24c217446d8760be7b7188711c2 >> >> Unfortunately musl-libc has a policy that musl is never wrong and thus >> it doesn't provide a #define __MUSL__ that you can test against to work >> around this kind of breakage, the way every other libc does. >> >> http://wiki.musl-libc.org/wiki/FAQ#Q:_why_is_there_no_MUSL_macro_.3F >> >> I did a quick stab at replacing sched_setscheduler() with a wrapper that >> calls syscall(NR_sched_setscheduler) but that musl commit broke _all_ >> the sched functions, sched_get_priority_max() and so on. I'd have to >> wrap all of them, even on systems that provide non-broken wrappers for >> the Linux syscall. >> >> This is why we have the TOYBOX_MUSL_NOMMU_IS_BROKEN config symbol, for a >> similar case where for 20 years nommu linux let you tell if you were >> building for a system with mmu or without it by a simple compile time >> probe: build a hello world that links against fork(); if it's not there >> it's a nommu system. Rich decided he didn't like that, and provided a >> broken fork() (always returns -ENOSYS) for nommu systems so you can't >> tell at compile time whether it's mmu or not. >> >> I'm trying to figure out if I should just leave chrt broken on musl and >> add a FAQ entry about it. If there was an #ifdef __MUSL__ I'd have the >> build produce a warning and the runtime produce a message, but of course >> there isn't... >> >> Rob >> _______________________________________________ >> Toybox mailing list >> [email protected] >> http://lists.landley.net/listinfo.cgi/toybox-landley.net > > > > -- > Elliott Hughes - http://who/enh - http://jessies.org/~enh/ > Android native code/tools questions? Mail me/drop by/add me as a reviewer. -- Elliott Hughes - http://who/enh - http://jessies.org/~enh/ Android native code/tools questions? Mail me/drop by/add me as a reviewer. _______________________________________________ Toybox mailing list [email protected] http://lists.landley.net/listinfo.cgi/toybox-landley.net
