Date: Sat, 23 Feb 2002 12:12:30 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Julian Elischer <julian@elischer.org> Cc: Bakul Shah <bakul@bitblocks.com>, Michael Smith <msmith@freebsd.org>, "George V. Neville-Neil" <gnn@neville-neil.com>, freebsd-hackers@freebsd.org Subject: Re: Kernel Debugging over the Ethernet? Message-ID: <3C77F7AE.76EAAE24@mindspring.com> References: <Pine.BSF.4.21.0202231022490.79221-100000@InterJet.elischer.org>
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Julian Elischer wrote: > > > The other issue with TCP is that you can set up specific > > > flows in the company firewall, and also permit SSLeay > > > based tunnel encapsulation from outside via an intermediate > > > machine. This isn't really required for off-site debugging, > > > but it gives another option. > > > > You are better off ssh-ing into a machine on the same net and > > running gdb there. This is really hard to do, when you are trying to debug a problem in the field in a situation that you can't repeat locally in your own lab, for whatever reason. The value of network debugging to me is not that I can avoid buying a serial cable (big deal), it's that I can do the debugging remotely. If I'm going to ssh into a local machine and debug from there, then I can use a serial cable. The other issue is that, doing remote debugging from a local machine, means I have to expose my source code on that machine. If I tunnel in, insteaD, well, then I'm not exposing the source code. > > For me the biggest reason for not using any IP was to > > minimize any perturbation due to the debugger. The fact that > > we have to steal mbufs is bad enough. > > I agree, especially when we will have locking etc for the mbuf queues. > It's a pitty we can't intercept the mbuf allocate routines.. > then we could keep a couple for ourself :-) IP is so you can make it through a cisco, etc. to another routable segment. For the allocation, you *can* intercept it. What you do is allocate a chunk of mbufs when you allocate other fixed memory in machdep.c. It's pretty trivial. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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