[ell-i-developers] Re: Hard fault handler

  • From: jigsaw <jigsaw@xxxxxxxxx>
  • To: ell-i-developers@xxxxxxxxxxxxx
  • Date: Sat, 24 May 2014 17:45:11 +0300

Yes it is supposed to be linked for debug purpose only. I've tested with
dedicated stack for fault handler, and it works fine. Thanks. -qinglai


On Sat, May 24, 2014 at 7:53 AM, Pekka Nikander <pekka.nikander@xxxxxx>wrote:

> > This problem can be resolved in 2 ways:
> > 1. Code everything in assembly in such a way that no stack is needed.
> > 2. Setup a stack by giving $sp an arbitrary address, after which point C
> code can start working.
> >
> > Pros and cons of both approach are obvious. I personally would like to
> have option 2 implemented in that I'm not very comfortable writing
> thousands lines of assembly.
> > The only shortcoming of option 2 is that the newly created stack may
> overwrite existing data which may be useful for locating the fault root
> cause.
> >
> > But again this issue can be resolved by allocating a private and small
> piece of memory in linker script. It can be as small as 512 or 256 bytes,
> which is usually big enough for not-deep-nested C routines.
> >
> > My questions is, is it acceptable to rob 256 bytes just for fault
> handling? (OK, the size is negotiable)
>
> I think the original idea was that the GDB hard fault handler would be a
> compile-time option that could be linked into the image or not?  If so, I
> think 256 bytes is perfectly fine.  Furthermore, quite often when
> developing embedded software the MCU used in the development environment
> has more memory than what is available in the actual production MCU.
>
> --Pekka
>
>

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