[U-Boot] [PATCH 2/2] Add check that console is ready before output

[Simon Glass]

Hi Wolfgang,

On Mon, Oct 17, 2011 at 1:37 PM, Wolfgang Denk <wd at denx.de> wrote:
> Dear Simon Glass,
>
> In message <CAPnjgZ3WBmJBs1zCd4_jQsUZcO2BOAOK865CaL6tWeUX9zVVWg at mail.gmail.com> you wrote:
>>
>> Yes indeed -  I did actually submit an 'early panic' patch which I
>> should take another look at - it is called 'Add board_panic_no_console
>> to deal with early critical errors'. I think it was in the same patch
>> set but I'm not sure.
>
> It was (I even commented on it).
>
>> It would panic when console output was performed before the console
>> was ready - and therefore give the behaviour you desire.
>
> Well, but there will probably be a large number of boards that don't
> implement this function (or don;t enable it if we make it
> configurable).  And all these will now fail silently.

Sorry, just emailed again on this thread - actually the behaviour of
that patch has already come in due to Graeme's patch.

And I think it is actually the opposite - they will not fail silently,
but in fact ignore the pre-console printf() and continue. Previously
(before Graeme's patch and this one had it been applied) any
pre-console printf() would cause a silent failure / hang. I think this
was the intent of the fix.

The intent of my other patch in the series was to provide a way for a
board to panic before the console is ready, and hopefully get a
message to the user (flashing lights, LCD, init all the UARTs and
blast out a msg, etc.). It is true that most boards will not implement
this. We could perhaps look at implementing a weak function to do this
at the architecture level (but only for SOCs) but it seems risky.

Regards,
Simon

>
> Best regards,
>
> Wolfgang Denk
>
> --
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
> panic: kernel trap (ignored)
>