Date: Wed, 06 Jul 2016 21:34:06 -0700 From: Matthew Macy <mmacy@nextbsd.org> To: "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: difference in SIGCHLD behavior between Linux and FreeBSD breaks apt Message-ID: <155c3a25e3f.11fb4143170445.2284890475527649192@nextbsd.org>
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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. Thanks in advance. -M
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