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.


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