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Re: Problem with "Happy Meal" drivers




On 1/11/2004 5:54 AM, ndade@jasiri.com wrote:
> On Sun, Jan 11, 2004 at 08:58:17AM +0100, bath66 wrote:
> 
>>"Andrew Sharp" <andy@ccpu.com> was quoted as saying by some wrong mail agent
>>operated by Mr. bath66 who should know better
>>
>>>Before you turn off the PC that is connected to the Sun's serial
>>>console, remove the cable from the sun.  That way, the sun will stay
>>>running and you won't have these problems.
>>>
>>
>>Thanks for the conseil .. It work now ... but can you explain me why ?
> 
> 
> A break signal on the sun serial port drops it into the openboot prompt.
> 'go' restarts it where it left off.
> 
> In rs232 a break is signaled by holding the line low for longer than
> 10 bit times (therefore it cannot be a valid byte b/c a valid byte
> would have ended with a high stop bit at the 9th bit[1]).
> 
> Some PCs inadvertently drive TX low for that long as power goes down.
> There isn't much you can do; I even tried lowering the baud rate
> and even as 1200 the PC's signal was long enough to act as a break.
> 
> -Nicolas Dade
> 
> [1] assuming 8N1; the principal is the same with other data settings---
> a break is unambiguously not a data transfer

Run this command to over come the hardware BREAK signal:
/sbin/sysctl -w kernel/stop-a=0

The above is the same as Solaris "/etc/default/kbd" with:
KEYBOARD_ABORT=disable



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