Date: Wed, 6 Jul 2016 21:52:24 -0700 From: "K. Macy" <kmacy@freebsd.org> To: Don Lewis <truckman@freebsd.org> Cc: "mmacy@nextbsd.org" <mmacy@nextbsd.org>, "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: difference in SIGCHLD behavior between Linux and FreeBSD breaks apt Message-ID: <CAHM0Q_O3Apy86DZqDBXnJJ6axMhVPu0xHngoJoHQqKe1QN4%2BgA@mail.gmail.com> In-Reply-To: <201607070443.u674hsgK007808@gw.catspoiler.org> References: <155c3a25e3f.11fb4143170445.2284890475527649192@nextbsd.org> <201607070443.u674hsgK007808@gw.catspoiler.org>
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On Wednesday, July 6, 2016, Don Lewis <truckman@freebsd.org> wrote: > On 6 Jul, Matthew Macy wrote: > > As a first step towards managing linux user space in a chrooted > > /compat/linux, initially for i915 testing with intel gpu tools, later > > on to get widevine and steam to work I'm trying to get apt to work. > > I've fixed a number of issues to date in pseudofs/linprocfs but now > > I'm running in to a bug caused by differences in SIGCHLD handling > > between Linux and FreeBSD. The situation is that apt will spawn dpkg > > and wait on a pipe read. On Linux when dpkg exits the SIGCHLD to apt > > causes a short read on the pipe which lets apt then continue. On > > FreeBSD a SIGCHLD is silently ignored. I've even experimented with > > doing a kill -20 <apt pid> to no effect. > > > > It would be easy enough to check sysvec against linux in pipe_read and > > break out of the loop when it's awakened from msleep (assuming there > > aren't deeper issues with signal propagation for anything other than > > SIGINT/SIGKILL) and then do a short read. However, I'm assuming that > > anyone who has worked in this area probably has a cleaner solution. > > It shoulds like SA_RESTART is set in sa_flags for SIGCHLD but shouldn't > be in this case. Good point. Thinking more about it, this seems like a bug in FreeBSD. Not a valid behavioral difference. -M > > _______________________________________________ > freebsd-current@freebsd.org <javascript:;> mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org > <javascript:;>" >
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