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Date: Wed, 12 Nov 2014 16:20:50 +0100
From: Thierry Bultel <tbultel@free.fr>
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Subject: Re: [Xenomai] IMX kernel 3.0.35_4.1.0 +
 adeos-ipipe-3.0.43-mx6q-1.18-14 -> very slow boot
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: nicolas Mabire <nicolas.mabire@basystemes.fr>, xenomai@xenomai.org

Le 12/11/2014 15:30, Gilles Chanteperdrix a écrit :
> On Wed, Nov 12, 2014 at 03:27:11PM +0100, Thierry Bultel wrote:
>> Le 12/11/2014 14:34, Gilles Chanteperdrix a écrit :
>>> On Wed, Nov 12, 2014 at 02:17:11PM +0100, Thierry Bultel wrote:
>>>> Le 11/11/2014 21:03, Gilles Chanteperdrix a écrit :
>>>>> On Tue, Nov 11, 2014 at 08:57:34PM +0100, Thierry Bultel wrote:
>>>>>> Le 10/11/2014 13:36, Gilles Chanteperdrix a écrit :
>>>>>>> You can use printascii in the timer interrupt acknowledge routine to
>>>>>>> print a character every HZ ticks, this will give bad latency, but
>>>>>>> should work.
>>>>>>>
>>>>>>
>>>>>> For unknown reason, the kernel gets stuck after
>>>>>> "console [tty0] enabled, bootconsole disabled" if I use printascii
>>>>>> in do_local_timer().
>>>>>> earlyprintk seems broken as well.
>>>>>
>>>>> Without doing this, does earlyprintk work?
>>>>
>>>> No it does not. In fact, this kernel is strange with early debug.
>>>> Namely, even without earlyprintk, when it comes to disable the
>>>> bootconsole to use the normal one, it uses then re-prints everything
>>>> was printed before, making think that it has restarted from the
>>>> beginning.
>>>>
>>>> I confirm that calling printascii in do_local_timer() leads to a
>>>> kernel panic. Same thing if I use __ipipe_serial_debug instead.
>>>> I have used a counter (one per cpu) to start logging after 30000
>>>> ticks and it crashes after that delay.
>>>
>>> Having looked at the sources, I do not find a debug-macro.S for
>>> imx6. So, I doubt printascii can work at all. Maybe a first step is
>>> to implement this missing support.
>>
>> I think that the implementation is in arch/arm/plat-mxc/include
>> /mach/debug-macro.S
>
> And the debug UART you are using is UART2 ?
>
Yes,
and I have found out why the logs before the console switch were 
displayed twice. This is because the BSP directly calls

early_console_setup(UART2_BASE_ADDR, uart_clk);

removing it does not make earlyprintk or printascii work better, 
unfortunately.