RTEMS Available -- PowerPC/virtex feedback

Joel Sherrill joel.sherrill at oarcorp.com
Fri Aug 10 16:49:49 UTC 2007

Chris Caudle wrote:
> On Fri, August 10, 2007 9:19 am, Joel Sherrill wrote:
>>          {"403", PROCESSOR_PPC403,
>>          {"405", PROCESSOR_PPC405,
> Doesn't that imply that the tools for PPC405 should already be using soft
> float?
Correct and the 403 is also soft-float. 

FWIW RTEMS only has a multilib for the 403 right now.  The
405 links with the 403 libraries which means that the 403 has
to be a proper subset of the 405 or you will get incorrect

DLMZB -- determine left most zero byte should only
result in improved strlen for 405.
HULMW -- appears to be hardware multiply and accumulate
so it might have some performance impact but that is unknown.

My conclusion is that the 403 is (from gcc's perspective) a proper
subset of the 405.
> Everyone is scurrying around figuring out how to rebuild tools with soft
> float, but it looks like that should be the default already, and so far no
> one has presented any code which confirms that the exception was actually
> caused by using a floating point register.
> Shouldn't looking at the instructions to see if that is a feasible
> explanation be the first step?


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