[Barrelfish-users] No serial input

[Simon Gerber]

Hi Andrew,

As far as I can tell, in the case where serial input does not work, 
serial_bind_cb never gets called and fish is waiting to dispatch an 
event in terminal_read. Do you have any idea why this is?

-- Simon

On Tue, 8 Nov 2011 12:51:48 +0000, Baumann  Andrew wrote:
> Hi Simon,
>
> I don't think this is the problem. serial_bind_cb() checks for
> state->want_stdin, and if so sends the associate_stdin message
> whenever it runs. This may be after terminal_want_stdin has returned,
> but that's fine as long as the message send doesn't fail. There is a
> problem that it has no way to report the error code if the message
> send fails, but in the current tree this should just result in an
> assertion failure and crash of the program, not silent failure. The
> only way I could see this failing silently in the way you describe is
> if you're compiling without assertions, in which case the error will
> go undetected. There should really be a USER_PANIC_ERR call in there
> rather than just an assertion to catch this.
>
> Cheers,
> Andrew
>
>> -----Original Message-----
>> From: Simon Gerber [mailto:simu at vis.ethz.ch]
>> Sent: Tuesday, 8 November 2011 13:06
>> To: barrelfish-users at lists.inf.ethz.ch
>> Subject: Re: [Barrelfish-users] No serial input
>>
>> Hi,
>>
>>  From what I can tell, if terminal_want_stdin needs to look up and 
>> bind
>> to the serial service, the code after the lookup runs before the 
>> bind_cb
>> completes and thus the check for state->serial != NULL before
>> associating stdin fails and terminal_want_stdin returns with 
>> SYS_ERR_OK
>> without having actually grabbed stdin.
>>
>> I assume this should be fixed by busy-waiting on the completion of
>> serial_bind_cb? Or is there a better way of doing this?
>>
>> Cheers,
>>
>> -- Simon Gerber
>>
>> On Sun, 6 Nov 2011 17:26:47 +0000, Baumann  Andrew wrote:
>> > Hi,
>> >
>> > This sounds like a startup race. I can't tell you the solution, 
>> but I
>> > can give you clues where to look: lib/barrelfish/terminal.c
>> > terminal_init() does a  nonblocking lookup for the serial driver, 
>> and
>> > if it is already registered, it connects to it. Otherwise if it 
>> isn't
>> > already present, fish's main() will start without a binding to the
>> > serial driver, but the call to terminal_want_stdin() should cause 
>> the
>> > binding to be established (this time in a blocking fashion), 
>> assuming
>> > you didn't pass "keyboard" as one of the command-line parameters 
>> to
>> > fish. I would stick some debug into terminal.c and try to 
>> understand
>> > what is happening when you block.
>> >
>> > Hope this helps,
>> > Andrew
>> >
>> >> -----Original Message-----
>> >> From: Mark Nevill [mailto:nevillm at ethz.ch]
>> >> Sent: Thursday, 3 November 2011 16:01
>> >> To: barrelfish-users at lists.inf.ethz.ch
>> >> Subject: [Barrelfish-users] No serial input
>> >>
>> >> Hi everyone!
>> >>
>> >> When booting Barrelfish repeatedly in qemu, rarely the two lines
>> >> below
>> >> appear:
>> >>
>> >> chips: client waiting for serial
>> >> chips: notifying client about serial
>> >>
>> >> If these lines appear, fish does not receive serial input.
>> >>
>> >> This particularly affects our pending merge of our AHCI driver
>> >> project, as we get these messages far more often (this is 
>> probably
>> >> due
>> >> to the AHCI driver delaying the initialisation of the serial
>> >> driver).
>> >>
>> >> Has anybody else encountered this issue?
>> >>
>> >> Regards,
>> >>
>> >> -- Mark & Simon
>> >>
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>>
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