Date: Wed, 16 Oct 2013 02:38:32 +0800 From: Jia-Shiun Li <jiashiun@gmail.com> To: Ian Lepore <ian@freebsd.org> Cc: "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org> Subject: Re: BBB triggered trap when disconnecting uart Message-ID: <CAHNYxxPncD8S3k53wow4TEQ2v1OO3_UexzTc6Dex=%2BgwA9wHfw@mail.gmail.com> In-Reply-To: <1381861694.42859.144.camel@revolution.hippie.lan> References: <CAHNYxxPe7maWJMNqXRV4YcpxSdHBv6pKDdMzyVLL8d3Kus7mbg@mail.gmail.com> <1381861694.42859.144.camel@revolution.hippie.lan>
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On Wed, Oct 16, 2013 at 2:28 AM, Ian Lepore <ian@freebsd.org> wrote: > Is the usb adapter you're talking about your console cable? If so, I > wonder if unplugging it is sending an rs232 break (a long string of 0 > bits) and that's dropping into the debugger? If that's the case, you > should be able to type "continue" at the db> prompt and everything will > resume running. > > It used to be possible to disable an rs232 break but enable the > alt-break sequence. I'm not sure if that's still the case (too busy to > go code-spelunking at the moment). > Unplugging cables on the BBB header side (3 wires) cause the same behavior. So it seems not term or dongle. And the term prints the kdb message before completely disconnected: login: KDB: enter: Break to debugger [ thread pid 838 tid 100053 ] Stopped at $d: ldrb r15, [r15, r15, ror r15]! db> ^R so I tried turn off _break_to_debugger sysctls, and then it can survive without being interrupted. Indeed this looks like what you said, sending break rs232 signal. Guess I need to have a proper sequence disabling break before disconnecting from BBB and turning off my PC. ;) Jia-Shiun.
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