[EdLUG] How to tell if a computer is 32 bit or 64 bit

[Edinburgh Linux Users Group]

On Sat, 30 Jul 2016, at 03:46, Edinburgh Linux Users Group wrote:
> Hi, thanks to everyone who replied.  I just learned that one needs to
> have 4 GB of RAM to take advantage of 64 bit GNU-Linux, so I am out
> of luck, as this machine only has 3 GB of RAM.  Is that true, am I
> out of luck?
>

You don't *need* to have 4GB RAM to use a 64 bit kernel. It will happily
work with less as long as you clear the minimum requirement for whatever
system you're installing.

I'd recommend using a 64bit kernel if the hardware supports it: that way
you can use either 64bit or 32bit userland applications. In debian (and
all the derivatives I've used) the multiarch support for installing both
side by side, and pulling in the right libraries, works well now.

I think worries about addresses being bigger and wasting memory are
overblown: if addresses/pointers make up even 1% of an apps memory use
I'd be very surprised (I have vague memories of an article actually
testing this that came to the conclusion of some small increase, but
can't find it now...). If you do find an app where it's noticeable[0]
you can always install the 32bit version of it. 64bit might offer some
run time advantages: it can "natively" operate on 64bits per
instruction[1], so for processing where that matters it'll be faster.

Robert

[] They might exist - if I was trying to be awkward I could certainly
write one.

[1] There were instructions that operated on 64bits (and wider) operands
    before x86_64 but they were special cases - the general purpose
    registers were 32bits, where they are 64bits in a 64bit system.
--
Robert McWilliam      rmcw at allmail.net    www.ormiret.com

Apparently, three out of four people make up 75% of the population.

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