64 bit and 32 bit OS

vinaytp · 12-04-2009, 01:58 AM

Hi all...

We have RHEL 64 bit and RHEL 32 bit OS, Where 64 bit OS runs on 64 bit machine architecture, but 32 bit can run on both 32 bit and 64 bit Machine architecture...

My doubt is in what sense 64 bit and 32 bit OS differ ? Are 64 bit OSes compiled in 64 bit Machine architecture and 32 bit OSes compiled in 32 bit Machine architecture ?

Confused...

Can anyone suggest me regarding this ...

Thanks in advance....

svinoba · 12-04-2009, 02:47 AM

Refer: http://www.tuxradar.com/content/ubun...bit-benchmarks
Hope you will find some useful info there.

johnsfine · 12-04-2009, 08:44 AM

Quote:

Originally Posted by vinaytp

We have RHEL 64 bit and RHEL 32 bit OS, Where 64 bit OS runs on 64 bit machine architecture, but 32 bit can run on both 32 bit and 64 bit Machine architecture...

An x86 32 bit Linux kernel can run on an x86 32 bit or 64 bit processor.

An x86 64 bit Linux kernel can run only on an x86 64 bit processor.

An x86 32 bit application program can run on an x86 32 bit kernel or an x86 64 bit kernel.

An x86 64 bit application program can run only on an x86 64 bit kernel. It cannot run on a 32 bit kernel even if that is on a 64 bit processor.

Quote:

My doubt is in what sense 64 bit and 32 bit OS

Kernel 32 vs. 64 bit affects the amount of physical ram the whole system can use, as well as whether you can run 64 bit applications.

Application 32 bit vs. 64 bit affects the amount of virtual address space that application can use as well as having a complex effect on performance (some programs are moderately slower in 64 bit. Others are moderately or significantly faster in 64 bit. Many aren't measurably different in speed).

Quote:

Are 64 bit OSes compiled in 64 bit Machine architecture and 32 bit OSes compiled in 32 bit Machine architecture ?

Yes.

vinaytp · 12-04-2009, 09:43 AM

Wonderfull johnsfine.....

Helped a lot

Thanks a lot...

resetreset · 12-06-2009, 10:01 AM

64-bit mode and 32-bit mode differ by a LOT of things, it isn't just the size of the registers - there's things like EPIC, which is available only for 64-bit.
There are some good tuts on Arstechnica (I think .com, just google), but they're quite technical, and also there's various PDF files you can d/l from AMD and Intel's sites which will tell you all about 64-bit, but I'm not sure whether you'll be able to follow them unless you're reasonably technically minded.
since you're in India, like me, have you noticed that *every* single cover DVD/CD that Linux For You magazine ships is a 32-bit version? Since that's the most common place to get your hands on a Linux DVD, in bandwidth starved India, I mentioned it to tell you that if you want a 64-bit distro, you'll have to download it yourself.