From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 6 Nov 2008 21:51:30 -0800 From: Roman Shaposhnik In-reply-to: To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Message-id: <616113E0-FF09-4A15-8216-286FC35A4D3F@sun.com> MIME-version: 1.0 Content-type: text/plain; delsp=yes; format=flowed; charset=US-ASCII Content-transfer-encoding: 7BIT References: Subject: Re: [9fans] Quick question on stopping a process that waits for IO Topicbox-Message-UUID: 3412f5c8-ead4-11e9-9d60-3106f5b1d025 On Nov 4, 2008, at 4:34 AM, erik quanstrom wrote: >> So the question remains -- what is the proper way of putting a >> process >> that waits for an IO into a Stopped state? > > i don't think it's possible without changing the kernel. > but it's a good question, why does it work this way? > obviously one doesn't want to stop a process and kernel work in > the middle of i/o. there may be locks involved, etc. > but one could easily check for Proc_stopme on syscall > exit. > > does anyone remember the thinking that went into this? I was waiting for somebody to chime in, but I guess no takers :-( Well, one last thing to report before we put this thread to rest would be the fact that acid(1) seems to be suffering from the same issue. If the process is doing I/O I can't modify the variables. Not a huge limitation, but a surprising one nonetheless if one draws from experience of working with conventional debuggers. Thanks, Roman.