On Fri, 27 Apr 2018 12:55:15 +0100, Gareth's Downstairs Computer wrote:

> On 27/04/2018 11:30, Jan Panteltje wrote:
>> On a sunny day (Fri, 27 Apr 2018 11:46:30 +0200) it happened Andreas
>> Neumann  wrote in :
>>
>>> Andrew Gabriel wrote:
>>>
>>>> Why do you want a 64 bit build?
>>>
>>> Because 64 bit are twice as good as 32 bit?
>>>
>>> SCNR
>>
>> Not even in theory, I did some web searching for that question myself,
>> wanted benchmarks.
>>
>> started reading here:
>>   https://raspberrypi.stackexchange.com/questions/49466/raspberry-pi-3-
and-64-bit-kernel-differences-between-armv7-and-armv8
>>   https://www.raspberrypi.org/forums/viewtopic.php?
f=66&t=138385&sid=9aaac4bc075db741ec8137e188b2956e
>>
>> Things may even slow down.
>>
>>
> Yes, but will improve all the time. In some ways like the specification
> for the processing of GSM mobile communication. ISTR that the needed
> technology was not around at the time of specifying, but every
> confidence was that it would appear.

In this case the only likely effect is that compiled executables will be
a bit bigger because a 64 bit pointer is 8 bytes compared with 4 for a 32
bit pointer and will run a bit slower because (I think) the 64 bit
pointer will need two fetches compared with one for a 32 bit pointer.

And, seeing that a 31 bits is a bigger address space than there is RAM on
an RPi3 (4GB  address space, 1GB RAM less that used by the GPU and screen
buffer), using 64 bit pointers gains you nothing.


--
Martin    | martin at
Gregorie  | gregorie dot org

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