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Date: Thu, 28 Jun 2007 09:43:40 +0100 (BST)
From: Robert Watson <rwatson@FreeBSD.org>
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To: Howard Su <howard0su@gmail.com>
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Cc: current@freebsd.org
Subject: Re: concept prove patch for ktrace output to all file types
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On Thu, 28 Jun 2007, Howard Su wrote:

> This is a concept prove patch for ktrace. In order to make ktrace write to 
> stdout, /dev/xxx, fifo file, pipe, I changed ktrace syscall to accepting a 
> file handler instead of a file name.
>
> I just get a workable kernel patch. And i make as small as possible changes
> to userland code. Now you can do something like:
> #mkfifo foo
> in session A: #kdump -f foo
> in session B: #ktrace -f foo ls
>
> Then, you can see a real time output like truss did.
>
> Before moving forward (hacking userland), i want to get some feedback if my 
> changes in kernel part is the right direction to do. Appreciate your time.
>
> PS: The patch can be clearly apply to today's current.

What happens to processes associated with the same or other ktrace sessions if 
one ktrace session stalls due to a fifo or pipe buffer filling?

Robert N M Watson
Computer Laboratory
University of Cambridge