[U-Boot] ARM926ej, trying to serve interrupt

[Wolfgang Denk]

Dear =?iso-8859-1?Q?Ricardo_Mart=EDnez?=,

In message <!&!AAAAAAAAAAAYAAAAAAAAAJp7zGtD32xAi3bhcLYAeQ3CgAAAEAAAAOIGRX5gEblKkejr+11MkVQBAAAAAA==@teltronic.es> you wrote:
>
> I'm trying to printf something when one timer generates an interrupt.

Hm... there are certain things you can do in interrupt contect, amd
certain things you cannot do.

Remember that in standard C you can in a signal handler  only  modify
vailables  of  type  sigatomic_t  -  you  must  not  call any library
functions, you must noit call any system calls. Well, in  praxis  you
will  probably  find  tat  system  calls  are  safe to call, and most
library functions can be used as well - but nly when you  know  their
implementation  well enough to understand exactly what they are (not)
doing.

Calling a printf() [which internally may need to allocate buffers, and
thus call malloc() and a lot of other complex functions] is something
you must never do ina signal handler.

Why do you think you can get away with the same here in U-Boot? Even
in interrupt contxt, which is probably even more restricitve?

> u-boot version is 1.3.4.

Old. OLD. I mean: OLD!!!  Please update.

> The problem is that when timer generates interrupt (reaches 0 after several
> cycles), I expect default u-boot code "do_irq", called from ".irq:" address
> defined in "start.S" get executed. In that function is where I want to
> printf anything to check it is working. But the whole system hangs. When
> timer generates the interrupt, ARM9 hangs without printing anything and
> normal execution is freezed.
>  
> printf and serial driver work perfectly because I've checked the steps above
> with prinft debugguing.

Is there any chance that the serial driver might be using interrupts,
too, and that you run into some nested interrupt  handling  which  is
not or not correctly supported by U-Boot?


Best regards,

Wolfgang Denk

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