64bit or not ?

[Matthew Geier]

Tino Schwarze wrote:
> On Tue, Jan 22, 2008 at 03:27:17PM +0100, Youssef Ghorbal wrote:
>
>   
>> 	As far as you're using distribution packages (deb, rpms and so) for  
>> software you are installing on 64bit machines every thing is allright.
>> 	But, if you compile your own softs from sources, you are going to  
>> regret 64bits systems with their /lib and /lib64 directories. Some  
>> libriairies are in the first and others are in the second and you are  
>> going to patch your ./configure and your Makefiles... I tried to  
>> compile PHP (with almost all extentions) on a RHEL EM64T system and  
>> didn't succeeded.
>>     
>
> These times should be over and the build systems should have been fixed
> by now.
>
>   

 Unfortunately, Linux 64 bit systems are split into two camps - the 
Redhat way and the Debian way.

 On the Redhat and related systems /lib is 32bit. Old applications 
compiled with bad assumptions as to were libraries are still work. The 
64bit arch is in /lib64 (and /usr/lib64)

 Debian and related (Ubuntu) put the 'native' arch in /lib (eg 64bit) 
and the 32bit library's are in /lib32.
 This breaks 32bit applications with bad assumptions that work on 
Redhat/Fedora.

 I've had this happen first hand - on 64bit Fedora many of my old Loki 
games (32bit) still work. On 64 bit Ubuntu, only Alpha Centuri works, 
the others all fail with dynamic link errors when they try to directly 
pull in library's out of /lib (wrong arch). Since Loki is no more, 
patches are unlikely to appear.

 Less of a problem with 'compile from source' but there is still scope 
for developers to make bad assumptions about what architecture is in /lib.

 Fortunately both 'worlds' have /lib32 and /lib64 :-)