Ok, I just got a new laptop a few weeks ago. It has a 64bit chip in it. I'm going to install linux on it but at the moment I only have 32bit versions on CD. Now if I install the 32 bit version, and then recompile the kernel to use a 64bit chip instead will it work? Or should I just bite the bullet and download a 64bit version?

That will not work. It will explode. The kernel isn't the only thing that needs to be 64-bit; the libc and applications need to be compiled for x64 as well. Download the 64-bit version.

Isn't the AMD64 chip supposed to emulate 32bit function for running 32bit programs? I am not sure I got the 64 bit version of Mepis but it works...I could just be crazy. Perhaps that is only in Windows.

Quote: Original post by tHiSiSbOb
Isn't the AMD64 chip supposed to emulate 32bit function for running 32bit programs?

Yes.

Snefel is dead right... you can't just recompile a 64bit kernel. You'd need libraries and other things as well.

Although Linux on x86-64 can also run i386 programs, I don't know whether it can run them exclusively (i.e. a completely 32-bit usermode).

Even if it can, having a 32bit usermode on a 64-bit kernel is not likely to gain much advantage.

In any case, you'd have to install a cross-compiler for i386 -> x86-64, which would probably involve getting the source to gcc and rebuilding that.

Cross-compiling kernels if of course entirely feasible (and necessary for embedded guys), but not for the faint hearted.

It would be much easier to just get a x86-64 distribution.

Mark

I think Ubuntu has some facility via apt (either through a package or changing your repository) that should upgrade your entire install to amd64. However, my wager is that would break a hell of a lot of things and cause you to end up tearing your hair out and checking into an insane asylum.

Probably best to just start from a good location; order the ubuntu amd64 CD.

And if you do install a 64bit OS doesnt that mean most 32bit programs wont run? I thought I heard that somewhere and that is the only thing keeping me from installing a 64bit OS.

Quote: Original post by lethalhamster
And if you do install a 64bit OS doesnt that mean most 32bit programs wont run? I thought I heard that somewhere and that is the only thing keeping me from installing a 64bit OS.

Under Win64, most Win32 programs will run fine, using the WOW64 compatibility layer. A couple will have problems, but they're the exception.

Under Linux64, programs compiled for Linux32 will only run if you set up a 32-bit library environment for them (I've done this on my Kubuntu installation, using instructions available online). But the vast majority of programs can simply be compiled for Linux64.

Quote: Original post by lethalhamster
And if you do install a 64bit OS doesnt that mean most 32bit programs wont run? I thought I heard that somewhere and that is the only thing keeping me from installing a 64bit OS.

Most of the Ubuntu packages have been ported to amd64 by now. You can also build programs from source, or set up a FreeBSD-like library emulation system.