[rtems commit] smpcapture02: Add test of functionality to add custom entries to capture trace

Chris Johns chrisj at rtems.org
Fri Feb 13 08:54:23 UTC 2015

On 13/02/2015 7:06 pm, Sebastian Huber wrote:
> On 13/02/15 08:56, Daniel Cederman wrote:
>> > Daniel(s), could enlighten me why this is needed ? Is this a arch
>> > constraint or something else ?
>> >
>> > Chris
>> It is an arch constraint. On SPARC, for example, all memory accesses
>> needs to a be aligned. From the SPARC V8 manual:
>> "Halfword accesses must be aligned on 2-byte boundaries, word accesses
>> must be aligned on 4-byte boundaries, and doubleword accesses must be
>> aligned on 8-byte boundaries. An improperly aligned address in a load
>> or store instruction causes a trap to occur."
>> Since the capture engine does a 64-bit write when it writes the time,
>> the entries needs to be aligned on 8-byte boundaries.
> If you need this hack in the test, then there is a bug in the caputure
> engine.

Agreed, and what I was wondering.

Maybe the capture engine needs a buffer alignment arg so the data 
transfers match up.


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