Memory bus is 64 bit but data access and register is only 32 bit for i386

lilzz · 09-01-2006, 02:07 PM

when the 32 bit register access the 64 bit memory is that mean the memory bus is not fully utilized?

pda_h4x0r · 09-01-2006, 03:16 PM

Could you give us more information on your system? 32-bit chips can be made to access 64-bit address space, but we don't know if its the case for your machine.

lilzz · 09-01-2006, 07:50 PM

for example
you can only do

movl $0x55555555, %es

%edx) moving 32 bit to memory location

you can't do

movq $0x5555555555555555, %es

%edx) illegal.
not such thing movq (64 bit access to memory)

what you mean by 64 bit access?
thanks

System P4

pda_h4x0r · 09-02-2006, 12:35 AM

Use the MMX registers. They are 64-bit and should be able to make use of a 64-bit memory bandwidth.

Here's an example:
http://www.jorgon.freeserve.co.uk/Te...elp/MMXins.htm