[ECOS] powerpc8270 exception management and redboot and ecos interaction

Gary Thomas gary@mlbassoc.com
Tue Jun 19 13:20:00 GMT 2007

Nelly PISON wrote:
> Hello,
> I use redboot and an ecos application on a powerpc 8270 board.
> 1 - powerpc exception management I use a function _reset developped on
> our hardware platform that made an exception (parity error) : this
> exception provoque the hard reset of the 8270:can you tell me where
> is  the source that treat  this exception.
> the code that made this exception is:
> {
>    unsigned long hid0, int_state;
>    // Need interrupts off to force checkstop
>    IMM->clocks_rmr |= 0x01;  // Checkstop Reset Enable
>    // Force a checkstop by turning on parity which is not implemented
>    hid0 |= 0x30000000;
>    while (1) ;
> }

There is no handler for this (in fact, it's pretty hard to write one!). 
This exception causes a checkstop
which in turn is setup to force a hardware reset (HRESET).
> 2 - reboot and ecos interaction
> - Where is the Dynamic memory allocation zone for redboot (if any) and
> the ecos application allocation : is that the same? ,
> if yes how can this work ?
> if not where can we see where is mapped the zone for each?

RedBoot uses fixed memory - eCos applications are set up to use
everything else.  Look at the
information printed when RedBoot starts to figure out the limits & layout.
> - Does the ecos application  call redboot after the appication is
> started?

Yes, RedBoot does provide _some_ limited services to the eCos
application.  In particular, diagnostic I/O
> If yes , What part of the ecos application can call the
> flash_get_config function with type  CONFIG_BOOL and key
> "info_console_force"?
Use the Virtual Vector interface for this.  The attached program shows
an example.

Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world

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