From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <036c01c423a7$21a3f3c0$57d87d50@SOMA>
From: "boyd, rounin" <boyd@insultant.net>
To: <9fans@cse.psu.edu>
References: <f4842ac25caa131d85c944aca3e1e7c8@proxima.alt.za>
Subject: Re: [9fans] waitpid()
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Date: Fri, 16 Apr 2004 13:36:38 +0200
Topicbox-Message-UUID: 5d2c710c-eacd-11e9-9e20-41e7f4b1d025

> So the big question is whether it is entirely out of the question to
> enhance the kernel "wait" functionality so that something resembling
> Posix waitpid() can return the termination information for a chosen
> PID.

don't do it in kernel mode.  do it in user mode.  just record the
pid + Waitmsg of the ones that wait has returned and search
this first and if not found go into a wait loop, recording the
pid + Waitmsg as wait returns if it's not the one you want,
otherwise return.

    The Waitmsg structure is allocated by malloc(2) and
    should be freed after use. For programs that only need
    the pid of the exiting program, waitpid returns just the
    pid and discards the rest of the information.

http://plan9.bell-labs.com/magic/man2html/2/wait