[fpc-devel] 64 bit version problem

Jonas Maebe jonas.maebe at elis.ugent.be
Wed Jan 30 10:56:55 CET 2008

On 30 Jan 2008, at 08:35, Michael Schnell wrote:

>> Yes, that is understable, because for example pointers are twice as  
>> big, which results in more memory accesses and less pointers in the  
>> CPU caches and more cache misses.
> Is this a software design decision (to allow for large projects  
> using > 4Gig Memory) or does the architecture not provide an  
> effective way of storing the low 32 bits of pointers in 4 byte  
> memory locations.

If you want 32 bit pointers, use a 32 bit program. Most 64 bit kernels  
support running 32 bit binaries (although not all userlands also  
support 32 bit binaries).

> (I suppose that in "small" processes the process address space is  
> 0...0xFFFFFFFF.)

That is not correct. Some OSes even mark the entire lower 4GiB as  
invalid for 64 bit processes.


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