Is setjmp patch still need for MVME550 with 4.10.2

[Kate Feng]

On 01/18/2012 12:08 PM, Till Straumann wrote:
> OK, got my memory up to speed.
> Here's some background:
>
> setjmp/longjmp save/restore the CPU context to/from memory.
>
> powerpc-RTEMS has had the option to use lazy floating-point and
> altivec context switching. This means that the ordinary setjmp/longjmp
> needed to be patched so that they only save FP and/or altivec registers
> for tasks which have the respective engines enabled (otherwise
> setjmp would crash, e.g., trying to save FP registers from a task
> context which is non-FP and has the FPU disabled).
>
> However, with increasing gcc optimization it has become very
> difficult to control exactly when gcc emits FP or altivec instructions
> (and it is not trivially possible -- due to subtle ABI changes -- to mix
> e.g., -msoft-float with -mhard-float compiled code).
>
> Therefore, IIRC, under rtems-4.10 the FPU (and altivec) engines
> are always enabled thus obsoleting the need for a setjmp/longjmp
> patch.
Yes, you are right but in RTEMS4.10.0 the altivec engine was not enabled on
mvme5500 BSP.  Thus, the patch at
https://www.rtems.org/bugzilla/show_bug.cgi?id=1786 would be a better one
for RTEMS4.10.0 instead of the setjmp patch.

In conclusion, setjmp patch is not need for MVME550 with 4.10.2 because
patch 1786 is applied starting 4.10.1.

Regards,
Kate

>
> HTH
> - Till
>
> On 01/18/2012 10:34 AM, Phillip Sorensen wrote:
>> Hello,
>>
>> I am in the process of upgrading from RTEMS 4.10.0 to RTEMS 4.10.2, and
>> I noticed that one of the patches for the update was for the MVME5500
>> BSP.  In the past I have had to patch newlib setjmp for this BSP.  Is
>> this newlib patch still needed for the lastest version or RTEMS?
>>
>> Thanks,
>>
>> Phil Sorensen
>> CHESS
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>
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