Installing a 64 bit OS or keeping a 32 bit OS?

[Michael R. Head]

On Fri, 2008-02-01 at 12:13 +0000, Chris Jones wrote:
> Jef Driesen wrote:
> > Chris Jones wrote:
> >>> Can I still run 32bit applications? 
> >> Yes, absolutely. You will need to install some 32 bit system libraries 
> >> along side their 64 bit versions (this may be default, I don't have a 64 
> >> bit ubuntu so cannot be sure here. Someone else who does can clarify this).
> > 
> > But if I install a 32bit application, I also need to install a 32bit 
> > version of all its dependencies? Or is that not necessary?

> Yes, any 32 bit application will need 32 bit versions all dynamic 
> libraries it needs. However, if you do this via apt/synaptic etc., this 
> should be done automatically for you.

It's not possible to install i386 packages on an amd64 install -- a
limitation of the dpkg system.

> I'm currently on a 64 bit redhat box, here the main 64bit system 
> libraries go in /usr/lib64 and /lib64 - However, in order to allow 32 
> bit binaries to run as well, the system also has 32 bit versions of the 
> same libraries in /usr/lib and /lib

Ubuntu on amd64 has:
burner at backdraft:~$ ls -ld /lib*
drwxr-xr-x 16 root root 8192 2007-12-08 07:35 /lib
drwxr-xr-x  4 root root 4096 2007-10-25 10:06 /lib32
lrwxrwxrwx  1 root root    4 2006-10-24 12:39 /lib64 -> /lib


> The names might be different on ubuntu, I don't have a 64bit version of 
> that so cannot be sure, but the principle is the same.
> 
> The 32 bit libraries where not there by default, but they where 
> available in the standard software repositories it uses (via yum/rpm) - 
> I'm sure ubuntu must have a similar thing ?

Ubuntu has ia32 compatibility packages, which need to be available for
various 32bit apps to run:
ia32-libs (contains 32 bit versions of gtk and a bunch of other standard
libraries)
ia32-libs-kde (contains 32 bit versions of the KDE libs)

as well, there are as some specific lib32* packages.

> > 
> >>> The laptop is mainly used for software development, so I would like to
> >>> have a 64bit environment for testing my code. But I still need to be
> >>> able to compile for a 32bit environment (and preferable test them as
> >>> well). Is that possible?
> >> yes, with gcc just use the "-m32" flag and that will force the 64 bit 
> >> compiler to build 32 bit binaries.
> > 
> > Does that also work when linking with other libraries? I suppose a 64bit 
> > Ubuntu will have only 64bit libraries installed. How do I build the 
> > 32bit binary in that case?
> 
> If you want to build 32 bit binaries, you will need to install 32bit 
> versions of all libraries you need to link against. See above.
> 
> Chris
> 
-- 
Michael R. Head <burner at suppressingfire.org>
http://picasaweb.google.com/demiri.head.wedding
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