---- On Mon, 18 Jul 2016 16:11:53 -0700 Alfred Perlstein <alf...@freebsd.org>
wrote ----
> I believe the
>
>
> On 7/6/16 9:34 PM, 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.
> >
> > Thanks in advance.
>
> Are you sure you need a hack in pipe_read and not one of the following
> possibilities:
> 1) a setting for the default signal disposition for linux processes
> needs to be fixed.
> 2) a flag set in p_flag2 that says set this behavior properly in a
> generic manner.
>
> Again not sure why you need to hack pipe_read and not just make sure
> that SIGCHLD is generated...
>
> Finally that sure is oddball behavior, dpkg probably has a bug where the
> parent is keeping the write side of the pipe open, you might be able to
> get them to take a patch upstream to fix that.
>
If you read my final mail it turns out I was holding a reference to the pipe in
question in linprocfs. Maintaining the reference kept apt from getting the EOF
on the pipe. I've since fixed this.
-M
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