64 bit on RTEMS

Kate Feng feng1 at bnl.gov
Sat Aug 1 01:21:17 UTC 2009

Leon Pollak wrote:
> On Friday July 31 2009, Kate Feng wrote:
>> Hi,
>>    Does RTEMS compiler truly support "64 bit DMA operation"
>> if the H/W (e.g. processor & data bus)  supports 64 bit data ?
>> What I meant is that the compiler will not chop down the
>> 64 bit data into two of 32 bit ones.  Please confirm.
> Kate,
> i am not sure what you mean...
> In my case, I have MPC8260 like CPU which has 64bit bus for RAM and DMA 
> transfers. This is done by CPU automatically.
> AFAIK, DMA is done without CPU intervention and compiler can not influence on 
> that.
Yes,  I actually thought the 64 bit DMA operation is independent of the 
CPU and
O.S.. I really meant other 64 bit data operations, which needs to be 
processed by a
64 bit CPU.  I thought currently the RTEMS compiler will perform two of 
32 bit data
operations instead of one 64 bit data operation.
> May be you mean 64bit machines such as AMD or INTEL Pentium Dual core etc.?
Yes, I meant the INTEL Pentium Dual core.  Does anyone have an RTEMS BSP for
it ?


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