Pyserial and Ubuntu Linux kernel 3.13.0-65-generic

[Rob Gaddi]

On Sat, 03 Oct 2015 11:12:28 +0200, Laura Creighton wrote:

> In a message of Sat, 03 Oct 2015 11:07:04 +0200, Laura Creighton writes:
>>In a message of Fri, 02 Oct 2015 22:36:23 -0000, Rob Gaddi writes:
>>>So, this is odd.  I'm running Ubuntu 14.04, and my system did a kernel
>>>upgrade from the repository from 3.13.0-63-generic to
>>>3.13.0-65-generic. And pyserial (2.7, installed through pip) stopped
>>>working.
>>>
>>>Specifically, when I make read() calls on a Serial object, I get the
>>>error
>>>
>>>serial.serialutil.SerialException: device reports readiness to read but
>>>returned no data (device disconnected?)
>>>
>>>This comes from the PosixSerial.read() method in serialposix.py, and
>>>seems to be a result of the select.select call screwing up.
>>>
>>>I reboot under 3.13.0-63-generic.  My code works.  I reboot under
>>>3.13.0-65-generic.  My code doesn't.  Implication would seem to be that
>>>somehow between these kernel versions, the select() logic in the serial
>>>driver changed.  This happens regardless of whether the serial port is
>>>real, FTDI USB-UART, or Prolific USB-UART.
>>>
>>>Can anyone else confirm?  Also, who do I try to report this one to?
>>>
>>>Thanks,
>>>Rob
>>>
>>>--
>>>Rob Gaddi, Highland Technology -- www.highlandtechnology.com Email
>>>address domain is currently out of order.  See above to fix.
>>>--
>>>https://mail.python.org/mailman/listinfo/python-list
>>
>>I think you have this bug
>>https://bugs.launchpad.net/ubuntu/+source/linux/+bug/460857
>>
>>or rather, you like the behaviour that ubuntu thinks is buggy, which
>>never got fixed, and don't like that it changed to be what ubuntu thinks
>>is correct in .65.
>>
>>I'd talk to the pyserial issue tracker as the people there ought to be
>>well aware of this problem, and then see if talking to ubuntu is the
>>right thing to do.
>>
>>Laura --
>>https://mail.python.org/mailman/listinfo/python-list
> 
> I think I said that poorly.
> 
> What I think happened is that ubuntu made some changes to fix this
> problem, and along the way they managed to break things for you,
> and maybe all pyserial users.  But I would talk to the pyserial people
> about that.
> 
> Laura

I'm not sure poorly as much as "could have offended someone who hasn't 
been caught by these sorts of issues before".  I took it as meant, that 
one person's bug is another's fix, rather than as "Your bug report is 
stupid and you should feel bad and never Python again."

And thanks for the find on https://bugs.launchpad.net/ubuntu/+source/
linux-lts-trusty/+bug/1501345.  That is PRECISELY what I should have been 
able to find.  I'll make only the excuse that it was late Friday with me 
having to run for the airport and I wanted to at least flag it as an 
issue before I hit the door.

-- 
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order.  See above to fix.