Re: Debug improvement

[Jonathan Larmour <jifl at eCosCentric dot com>]

Gary Thomas wrote:
> While debugging some thread problems recently, I turned on asserts and 
> thread stack checking only to find the results less than useful.  Yes, 
> the checking code detected the error (most times), but I was unable to 
> get useful information from GDB (I set a breakpoint at 
> cyg_assert_fail).  This was because the stack had been trashed severely.
Although if the stack is that dead, it's not clear a diag_printf would 
work any better!

> What I ended up doing was augmenting the stack check to provide a simple
> dump when an error was detected (along with the assert).  By being able 
> to see the dump, I was able to get more information and move along.
>
> My question is: what do y'all think of making such a change permanent.  
> I know that we've tried to keep most of these interfaces pretty pristine
> (no prints, no dumps, etc), but what's there didn't help me and I'm sure
> that others in the world (certainly ones with less experience with eCos 
> than I) would have been "stuck" with the existing support.
I think it's fine personally, although it might be a fraction clearer by 
removing the subsequent CYG_ASSERT and replacing it with a CYG_FAIL within 
the if block. And you may as well do the same for top[i] for symmetry. And 
maybe refer to it as "word at location %d in:\n", i*sizeof(cyg_uint32) 
again for clarity.

As long as CYGNUM_KERNEL_THREADS_STACK_CHECK_DATA_SIZE is always going to 
be a smallish number like 32 anyway (otherwise the output might be 
unhelpfully long), but I'm sure it will.

Jifl
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