Can 750 user-mode binaries run on a 603e core?

[Kumar Gala]

On Jul 27, 2006, at 10:30 AM, Andy Fleming wrote:

> Branch delay slots are evil, and PowerPC did not use them.
>
> 'nuff said.
>
> Pretty much any powerpc binary should work on any PowerPC system.
> Actually, we use a 603-compiled root file system for our e500
> processors (in our lab), and don't run into any problems.  This is

Let's be clear, that is done by emulating the floating point  
instructions in the kernel.  (And there are a few user space integer/ 
control instructions that e500 doesn't implement, but your rarely run  
into them).

- k

> On Jul 27, 2006, at 07:36, Jerry Van Baren wrote:
>
>> Patrick J. Kelsey wrote:
>>> (sorry about that last one. had a bit of trouble with a certain
>>> web based mail client...)
>>>
>>> Thanks for the reply, Kumar.
>>>
>>> That sounds encouraging.  One of the things I was worried about with
>>> scheduling differences would be a differing number of branch delay
>>> slots between the two core versions.  I'm still a bit new to the
>>> details of the PowerPC architecture, and at this point I'm not even
>>> sure if there are branch delay slots, although it does seem from my
>>> reading that the 603e and 750 pipelines are the same, in which case
>>> there would ceratinly be no worries here.
>>
>> FWIIW, the PowerPC architecture has hardware instruction interlocking
>> and scheduling and doesn't require the compiler to implement the
>> branch
>> delay slots like, for instance, the MIPS architecture.  This is much
>> more compiler and portability friendly, but at the expense of more
>> logic
>> in the processor (the PowerPC is not nearly as minimalistic as the
>> MIPS).
>>
>>> At this point, I'm not concerned so much about an inefficient
>>> schedule resulting from running -mcpu=750 code on a 603e as long as
>>> the execution is correct.
>>>
>>> Pat
>>
>> gvb
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