Near Last Call Before Branching 4.11

[Joel Sherrill]

On 7/16/2015 1:59 PM, Peter Dufault wrote:
>
>> On Jul 16, 2015, at 13:55 , Joel Sherrill <Joel.Sherrill at oarcorp.com> wrote:
>>
>> I am in the middle of a build sweep now with the tms570 patches
>> and my bsp.h changes. Once this finishes, I plan to push those
>> changes and cut the branch.
>>
>> Speak now.
>
> I have a two concerns but they’ll have to be fixed after the branch.  This is Phytec MPC5554.
>
> - My flash code had a dereference of the NULL pointer (expected) and it triggered the GCC -O2 optimization that replaced it with a TRAP instruction.  When I disassembled the application binary there were 39 calls to a TRAP instruction total, many in RTEMS code.  I recompiled with -fno-delete-null-pointer-checks (both RTEMS and my application) and there were 2.  I haven’t had time to go back and analyze this.

I wonder if this is something we should turn on by default. But more
investigation would be required before we did that.

> - I was having NFS crashes regularly.  I removed a pthread_mutex_trylock() in an ISR (I assumed that was safe) while trying to make that ISR faster and the NFS issues disappeared.  I haven’t had time to go back to that either.

There are checks against that. I don't remember the exact restrictions and
it may be completely forbidden. But depending on the configuration of the
mutex, it doesn't even make sense. Priority inheritance and ceiling imply
an owner thread so lock operations need to be from threads for mutexes.

You probably could have gotten by with a semaphore but wouldn't have had
the nice properties of a mutex.

> On a plus note the -ffunction-sections -fdata-sections size optimization has worked great and I didn’t need to make any changes other than rebuilding with that.

I am glad to hear this. It looked promising to turn on. Just required
testing on a per BSP basis.

> I’m on a project that’s late and that’s why I haven’t kept up on this.
>
> Peter
> -----------------
> Peter Dufault
> HD Associates, Inc.      Software and System Engineering
>

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill at OARcorp.com        On-Line Applications Research
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