Messages in this thread | | | Subject | Re: A question about break and sysrq on a serial console (2.6.19.1) | From | Brian Beattie <> | Date | Thu, 18 Jan 2007 08:52:49 -0800 |
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On Thu, 2007-01-18 at 16:47 +0000, Russell King wrote: > On Thu, Jan 18, 2007 at 08:19:47AM -0800, Brian Beattie wrote: > > On Thu, 2007-01-18 at 09:13 +0000, Russell King wrote: > > > On Wed, Jan 17, 2007 at 03:56:54PM -0800, Brian Beattie wrote: > > > > I'm trying to do a SYSRQ over a serial console. As I understand it a > > > > break will do that, but I'm not seeing the SYSRQ. In looking at > > > > uart_handle_break() in drivers/serial/8250.c it looks like the code will > > > > toggle port->sysrq, rather than just setting it when the port is a > > > > console. I think the correct code would be to move the "port->sysrq = > > > > 0;" to follow the closing brace on the next line, or am I missing > > > > something. > > > > > > Thereby preventing the action of <break> (which may be to cause a SAK > > > event, which would be rather important on a console to ensure that > > > you're really logging in rather than typing your password into another > > > users program which just looks like a login program.) > > > > > > Note that the sequence for sysrq is: > > > > > > (non-break characters or nothing) <break> <sysrq-char> > > > > > well the code as is, is not working. Printk's tell me that > > uart_handle_break() is called repeatedly while the break condition is > > active, toggling port->sysrq so that it's a 50/50 chance on whether > > port->sysrq will be set or cleared when the break condition ends. On > > the other hand the 8250 break condition handling code is not working > > anyway, so the problem may be that the 8250 code is not calling > > uart_handle_break() correctly. > > Please learn to use the "reply to all" button when using mailing lists. I don't post much to LKML, I realized after I hit send I needed to reply all. > > Works fine here. Which UART are you actually using? At a guess, it's > probably a bad clone which does not have a correct break implementation.
it's the built-in mpc8349 powerpc uart.
> -- Brian Beattie Firmware Engineer APCON, Inc. BrianB@apcon.com
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