Date: Thu, 9 Jul 2015 11:41:45 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Peter Jeremy <peter@rulingia.com> Cc: Garrett Cooper <yaneurabeya@gmail.com>, Doug Rabson <dfr@rabson.org>, Jamie Landeg-Jones <jamie@dyslexicfish.net>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: gettimeofday((void *)-1, NULL) implicates core dump on recent FreeBSD 11-CURRENT Message-ID: <20150709084145.GI2080@kib.kiev.ua> In-Reply-To: <20150708222717.GE98562@server.rulingia.com> References: <CAPQ4ffuTcN_ytcH7GPY0s6OqWK9qo6MGaVZhOB%2B0ojWfd=fNCg@mail.gmail.com> <201507072241.t67MfsX5085860@hergotha.csail.mit.edu> <94BCDA65-5B86-4329-A312-4CB16E847B69@dons.net.au> <CAPQ4ffuuaiWGUthEhux2VrK6ZyHDT=0xd9z8k8f11N=6shdUng@mail.gmail.com> <201507081616.t68GGcY9047713@dyslexicfish.net> <CACA0VUhFjBhPMTr=QD71jEvis9CMSrnpyu=xFiXu27nLeozGJA@mail.gmail.com> <0C541CE5-C322-4273-AE0B-1ACAEACCA096@gmail.com> <20150708222717.GE98562@server.rulingia.com>
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On Thu, Jul 09, 2015 at 08:27:17AM +1000, Peter Jeremy wrote: > I'm not sure if we want to explicitly document the conditions under which > gettimeofday() (or clock_gettime()) are implemented in userland vs syscalls > because that is guaranteed to get stale over time. How about stating that Of course, we don't. There is no guarantee that the set of conditions is stable even on the stable branch. > these functions are implemented as syscalls only if the AT_TIMEKEEP value > reported by "procstat -x" is NULL. Mere presence of AT_TIMEKEEP does not imply the use of the fast path. E.g. the fast path can be disabled dynamically, or timecounter could be changed, or libc might be of the wrong version. My imagination stops there. IMO the point of this discussion is to note that test suite tests useless things. If somebody run the test suite for libc, she would immediately note another failing test for the stack protector, which is similar to the gettimeofday nonsense.
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