build 64-bit apps under i386 Kubuntu on an AMD64 machine

[David J Bush]

I'm generally satisfied with i386 Kubuntu running on my dual core 64-bit Athlon box. The graphics look fine to me. But there are some apps I would like to be able to use the full power of my machine. These apps do a lot of intensive calculation. For example, chess engines, fractal zoom image generators, and povray would all benefit. But if I follow the standard sequence of ./configure, make, and sudo make install, the configure script would just read the target architecture as 32-bit, and would compile accordingly. Is that right? Or did I miss something? Is there any way I could tweak some initialization file or something to build these apps the way I want? Would there be any issues involved with getting them to behave under the 32-bit OS?

Thanks!

[Mr. Swiveller]

I know you can run 32-bit apps on 64-bit Kubuntu if you force-install them. I have never heard of this being possible the other way around, though.

In any case, I think that moving to 64-bit Ubuntu would ultimately be the best solution in your case, assuming that you are prepared, and have the time necessary, to migrate your files to a new OS.

I run 64-bit Kubuntu on my PC, and have yet to come across any disadvantages - all of the applications I use are available, and the system runs smoothly.

Oh well, I hope this is some help.

* Swiveller *

[Temüjin]

If you just had a few apps in mind for 64-bit goodness, you could look into making a chroot environment.

Really though, it's time to bite the little bullet and install the amd64 version when Hardy/8.04 is released.

[David J Bush]

Okay, looking up "chroot environment" in the Ubuntu help pages I find this warning:

"Make sure to install at least the version of debootstrap that is from the Ubuntu release for which you are trying to create the chroot. You may have to download it from packages.ubuntu.com (http://packages.ubuntu.com/) and manually install it with dpkg -i."

debootstrap depends on binutils and wget, which in turn have dependencies and so on. Would the 32-bit packages that make up this dependency tree satisfy a 64-bit debootstrap?

Also, they warn me that "creating a chroot environment will take some time." Ah, how much time on a dialup modem? A ballpark estimate would be helpful. Ironically, I do have an install DVD for 64-bit Gutsy, but when I try to add it to the sources list, my 32 bit OS can't read the disc.

This is an interesting exercise if nothing else. Thanks for any help.

[Kilz]

Okay, looking up "chroot environment" in the Ubuntu help pages I find this warning:

"Make sure to install at least the version of debootstrap that is from the Ubuntu release for which you are trying to create the chroot. You may have to download it from packages.ubuntu.com (http://packages.ubuntu.com/) and manually install it with dpkg -i."

debootstrap depends on binutils and wget, which in turn have dependencies and so on. Would the 32-bit packages that make up this dependency tree satisfy a 64-bit debootstrap?

Also, they warn me that "creating a chroot environment will take some time." Ah, how much time on a dialup modem? A ballpark estimate would be helpful. Ironically, I do have an install DVD for 64-bit Gutsy, but when I try to add it to the sources list, my 32 bit OS can't read the disc.

This is an interesting exercise if nothing else. Thanks for any help.

I think the idea of a chroot was meant to show you that a 64bit install would be a better idea. A chroot will be an install, inside an install. It will take as long as downloading a complete 64bit install would. Along with the huge amount of hard drive space, they are hard to setup and configure. This is a reason not many people use them anymore. It is easy to get 32bit applications running on a 64bit install without a chroot (not that any are required).

[gsmanners]

Another thing to try would be KVM or some other virtual environment for your 64-bit programs. You'd have to install a complete 64-bit OS, but you'd have that ability then.

[David J Bush]

What about a source file package which is not listed in any repository. It doesn't depend on any other packages, and no packages depend on it. I want it to compile for the AMD 64 architecture. Would I need a chroot environment for that? I just want to change the .config.ini file, or use some command line option when I call configure, or hopefully something similar so the compiled package will run in 64 bit glory.

Thanks for your time.

EDIT: On second thought, the package does require kde headers.

[Kilz]

What about a source file package which is not listed in any repository. It doesn't depend on any other packages, and no packages depend on it. I want it to compile for the AMD 64 architecture. Would I need a chroot environment for that? I just want to change the .config.ini file, or use some command line option when I call configure, or hopefully something similar so the compiled package will run in 64 bit glory.

Thanks for your time.

EDIT: On second thought, the package does require kde headers.

It is not possible to run a 64bit application on a 32bit install. But it is possible to install a 32bit application on a 64bit install. A chroot is a complete 64bit install inside a 32bit install, thats why it works. But there are other issues. If you have the room why not do a duel boot 32/64bit system to see if there are any issues that would keep you from running a 64bit system.

[Half-Left]

When you compile something in x86_64 then it takes the compiler flags from the compiler, which would be x86_64, you shouldn't need to change anything.

Only mame do you have to set the compile flags in it's own file.

[Temüjin]

I think the idea of a chroot was meant to show you that a 64bit install would be a better idea. A chroot will be an install, inside an install.

Exactly. DJB, it seems you're looking for a painless (in terms of time/effort) solution here and there isn't one. Embrace the suck, backup your data, repartition for a dual-boot (or better yet, commit to 64-bit and just keep your /home folder). Let us know when you're ready and we'll help you through it.