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List:       gpsd-dev
Subject:    Re: [gpsd-dev] Linux kernel bug in 3:12, low_latency on serial ports is broken
From:       Beat Bolli <bbolli () ewanet ! ch>
Date:       2014-02-22 22:25:58
Message-ID: 530923F6.8050601 () ewanet ! ch
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It looks like help is on the way:

https://lkml.org/lkml/2014/2/22/44

Cheers,
Beat

On 20.02.14 12:14, Beat Bolli wrote:
> Hi Hal
> 
> I had reported this to linux-serial:
> http://marc.info/?t=139125913700001&r=1&w=2
> 
> I could not make sense of the replies, however.
> 
> serial.c does not mention "low-latency" at all. Is the port->low_latency
> flag set by
> "session->ttyset.c_cc[VMIN] = 1;" in serial.c:494?
> 
> Regards,
> Beat
> 
> On 2014-02-20 09:31, Hal Murray wrote:
>> Just a heads-up in case you hit this, or want to avoid it.
>>
>> The symptom is BUG: scheduling while atomic
>>   https://bugzilla.redhat.com/show_bug.cgi?id=1065087
>>
>> The discussion at
>>   https://lkml.org/lkml/2014/2/18/77
>> confirms that it's the low-latency path that is buggy.
>>
>> My setup works fine under low load, but hits the BUG when I do
>> something like
>> compile the ntp package.
>>
>> 3.11 works fine.  (for me)  There was major work in the serial area
>> for 3.12
>>
>> I'll send an update when/if it gets fixed.
> 


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