[gclist] 64 bit machines and conservatism

Marc Feeley feeley@IRO.UMontreal.CA
Mon, 15 Dec 1997 13:51:25 -0500 (EST)

Charles Fiterman wrote:
> 64 bit machines permit a total rethink of operating system archetecture.
> 64 bit address space permits individual addressing of all the memory
> in the world even data on music CD's in people's homes. 
> So you could give all the data in the world independent addresses.
> Your ram has copies of some for cashing but your disks all have
> address ranges and other machines have address ranges and every
> word of data in the world has its own address.

I understand all of this and agree that there are neat possibilities.
However it is unrealistic to double the space requirements of an
application unless there is a really really compelling reason to do so
(i.e. more than "look... by dereferencing this pointer I can change
the settings on my grandma's toaster!").  A more practical approach is
to somehow segragate 32 bit pointers (local stuff) and 64 bit pointers
(possibly remote stuff) so that 64 bit pointers only show up in a few
places.  I bet that for most applications the 32 bit pointers
will far outnumber the 64 bit pointers.