From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH 5/5] lib/cobalt/clock.c:dispatch clock_settime References: <1604372743-2986-1-git-send-email-chensong@tj.kylinos.cn> <0ca03935-6895-f31e-f9ad-c910e0e22e36@siemens.com> From: chensong Message-ID: <5FAB60C5.8030909@tj.kylinos.cn>+8F6DBCED54AD750E Date: Wed, 11 Nov 2020 11:55:49 +0800 MIME-Version: 1.0 In-Reply-To: <0ca03935-6895-f31e-f9ad-c910e0e22e36@siemens.com> Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka , xenomai@xenomai.org, henning.schild@siemens.com On 2020年11月10日 18:24, Jan Kiszka wrote: > > On 03.11.20 04:05, chensong wrote: >> Regarding sizeof time_t, dispatch 32bit timespec to clock_settime >> and 64bit timespec to clock_settime64. >> >> Signed-off-by: chensong >> --- >> lib/cobalt/clock.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/lib/cobalt/clock.c b/lib/cobalt/clock.c >> index 11fd1aa..44b2f3f 100644 >> --- a/lib/cobalt/clock.c >> +++ b/lib/cobalt/clock.c >> @@ -237,7 +237,11 @@ COBALT_IMPL(int, clock_settime, (clockid_t clock_id, const struct timespec *tp)) >> { >> int ret; >> >> - ret = -XENOMAI_SYSCALL2(sc_cobalt_clock_settime, clock_id, tp); >> + if (sizeof(time_t) > 4) >> + ret = -XENOMAI_SYSCALL2(sc_cobalt_clock_settime64, >> + clock_id, tp); >> + else >> + ret = -XENOMAI_SYSCALL2(sc_cobalt_clock_settime, clock_id, tp); > > Maybe do a single > > XENOMAI_SYSCALL2(sizeof(time_t) > 4 ? sc_cobalt_clock_settime64 > : sc_cobalt_clock_settime, ...) > > But we need ABI revision negotiation here. If a new lib is run on a > kernel that does not have settime64, things will fail (the other way > around is fine). We need to ensure that new userspace can check for this > upfront while old userspace will happily run (hard requirement for > making these patches part of 3.1.x). > > Jan As far as my understanding, ABI revision negotiation happens in low_init already, it reminds userspace process that lib and kernel are not compatible at the first place. Therefore, it addresses the scenario you are talking about(new userspace, old kernel or the other way around). what's more, do we or customers release lib without kernel. About y2038, vanilla kernel, glibc, libcobalt, xenomai, too many scenarios to be addressed, to complicated, we'd better simplify it if possible. chensong > >> if (ret) { >> errno = ret; >> return -1; >> >