On 08/03/2010 10:01 AM, wrote:
>>> Maverick Crunch (TM): maverick as in selling fundamentally screwed silicon
>>> and discontinuing the product before ever releasing a working version.
>>> Crunch as in brick wall for all the mugs thinking they bought floating
>>> point capable hardware.
>>>
>>>
>> Its terrible. Probably the worst "FPU" ever made.
>>
>> From reading the bugs there are some pretty serious ones in there -
>> like an invalid operation leading to memory corruption. (So much for
>> security.) Its also 11 cycles per operation - so its faster than
>> software FP; but pretty poor overall.
>>
> Is this buggy FPU only in the 200MHz versions of the ARM9-based TS-boards, or
> does it also affect the 250MHz and 500MHz?
>
>
The problems we're speaking about here only affect the Cirrus ep93xx
based boards. The ep93xx chip is perfectly stable with the FPU turned
off. We built the alert me hub around an ep9302 - the ts7400 served as
the development platform for it. The chip is rock solid, provided that
one provides a proper reset fix (TS does this in their CPLD).
As long as your application can be designed to work with fixed point
(integer) arithmetic, then the TS ep9302 based boards are excellent, and
a well tested solution.
> Can I disable FPU usage all together in the kernel and/or clib so I'm certain
> the FPU won't be used?
>
Yes. Default kernel configuration is this way. (I have never deployed
a FP kernel on this chip. I have built one or two for testing though.)
> I was initially interested in the TS-7260 but perhaps it's worth choosing
> TS-7550 instead. Unfortunately it doesn't have any ADCs...
>
The Cavium chip is faster than the ep9302; I think its just a better
tuned Arm 9 and memory subsystem. The Atmel one looks like the fastest
that TS sells at the moment. I don't think either of them have FPUs.
The tradeoff sounds like either you building hardware A/D converters, or
a slower CPU with the 7260.
-Brett
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