32 bit apps on 64 bit processor

khaleel5000 · 04-16-2006, 04:36 AM

Hello
I have a question ... that on a 64 bit processor ,
u have 2 install 64 bit os but CAN u run 32 bit applications
on a 64 bit processor ..... ALL OF THEM (in linux and improtantly windows [my family uses windows] only i use linux .... please dont talk abt migration])
and cant 32 bit OS get installed on them (if apps can? ) any thing i might consider before buying a 64 bit system .. i mean any unforseen consequences

macemoneta · 04-16-2006, 07:39 AM

If you are planning on running 32-bit OS/applications, why pay for a 64-bit processor?

To answer your question, yes, all 32-bit applications work on a 64-bit x86_64 processor.

khaleel5000 · 04-16-2006, 11:58 AM

by 64 bit x 86_64 bit processor u mean all 64 bit or some (i mean i think x86 is if INTEL right????????)
also do u mean also 32 bit OS would work ??.... and what about my existing 32 bit linux distro ?? do the KERNEL thing and its all running?

peter_89 · 04-16-2006, 12:16 PM

Quote:

Originally Posted by khaleel5000

by 64 bit x 86_64 bit processor u mean all 64 bit or some (i mean i think x86 is if INTEL right????????)
also do u mean also 32 bit OS would work ??.... and what about my existing 32 bit linux distro ?? do the KERNEL thing and its all running?

I'm not totally sure I understand what you are asking, but the important word here is code. 32-bit code is 32-bit code, it doesn't matter whether it comes in the form of an application or an operating system.
Now, realize that "x86" does not only mean Intel, even though the term is derived from one of their products. It just means x86 compatibile -- in other words, a processor that can run the same machine code that Intel's processors can. This is important to understand because AMD's processor line is x86 compatible, meaning it can run all the same stuff Intel's line can -- leaving no difference to a user like you.
Either way, all new 64-bit processors today are capable of running both types of code -- 32-bit and 64-bit -- so yes, your current 32-bit distribution would work, but with a 64-bit processor, so would a 64-bit distribution.
(By the way, I highly recommend you spend the extra fifty dollars on a 64-bit processor. Hardly any users use 64-bit operating systems now, but in four or five years when the market will be booming, you'll already be ahead of the curve when everybody else is debating on whether to upgrade or not.)

masonm · 04-16-2006, 01:49 PM

Yes a 32 bit OS will run on a 64 bit processor.

khaleel5000 · 04-17-2006, 03:03 AM

okiez and what if i being a !@#$!@#^$# newbie a) use a 64 bit OS (can i install a 32 bit programme on it? ) ?
b) or a 64 bit programme on a 32 bit os?

macemoneta · 04-17-2006, 07:09 AM

You can install a 32-bit application on a 64-bit OS, on a 64-bit x86_64 platform.

You cannot install a 64-bit application on a 32-bit OS.

khaleel5000 · 04-17-2006, 07:49 AM

ok now just if u can answer my another question posted in this form link is
http://www.linuxquestions.org/questi...55#post2203555

it would be exponentially appriciated

Fireball7 · 04-17-2006, 02:06 PM

Just one more response to your question: yes and no. A 'true' 64 bit cpu will not run a 32 bit program, os, etc. However most processors on the market today are hybrids (such as amd's athlon 64), which can run both. No worries, though, just have fun building your compy.

peter_89 · 04-17-2006, 03:54 PM

Quote:

Originally Posted by Fireball7

Just one more response to your question: yes and no. A 'true' 64 bit cpu will not run a 32 bit program, os, etc. However most processors on the market today are hybrids (such as amd's athlon 64), which can run both. No worries, though, just have fun building your compy.

True. But don't worry about accidentaly buying a "true" 64-bit processors, since all of the 64-bit CPUs that you are even going to see WILL be hybrids.
"True" 64-bit CPUs these days are used for enterprise-grade servers.

primo · 04-19-2006, 02:39 AM

Quote:

Originally Posted by macemoneta

You can install a 32-bit application on a 64-bit OS, on a 64-bit x86_64 platform.

You cannot install a 64-bit application on a 32-bit OS.

Not true. It depends on what we need from 64-bits (larger virtual memory space or just numbers). Try this:

Code:

#include <stdio.h>
#include <stdint.h>

int main(void)
{
        uint64_t x = ~ 0;       /* "unsigned long long" may be used too */
        uint32_t y = ~ 0;

        printf("sizeof(x) = %u, sizeof(y) = %u\n", sizeof(x), sizeof(y));
        printf("x = %llu\n", x);
        printf("y = %u\n", y);
        return 0;
}

spooon · 04-19-2006, 03:40 AM

Quote:

Originally Posted by macemoneta

You can install a 32-bit application on a 64-bit OS, on a 64-bit x86_64 platform.

Yes... BUT note that 32-bit apps require the 32-bit versions of various libraries, while 64-bit apps require 64-bit versions of the same libraries; so there needs to be a way for them to coexist.

macemoneta · 04-19-2006, 07:55 AM

primo: The issue isn't building from source. You can build from source for most any platform. The issue for most is running a 32-bit x86 binary on an x86_64 platform running an x84_64 distribution. In that case, for binaries built non-statically, the issue is the installed libraries as spooon pointed out.

spooon: The x86_64 distributions use lib64 directories in addition to lib directories, which allow the coexistence of both 32 and 64-bit versions of the same library (e.g., /usr/lib and /usr/lib64). As a result, 32-bit and 64-bit prebuilt binaries can coexist peacefully.

For example, I prefer to use the 32-bit Firefox on my x86_64, because it is compatible with 32-bit only plugins. So I remove the existing (64-bit) Firefox, add the i386 repositories to yum, and:

yum -y --enablerepo=*386 install firefox

32-bit (i386) requisite libraries are installed in /usr/lib, and there is no conflict.