comps discussion at fudcon and the future

[Florian Festi]

Matthew Woehlke wrote:
> Florian Festi wrote:
>> Multilib:
>> The situation has changed a lot since we introduced multilib. The 
>> challenge
>> who is going to support 64bit processors first has been decided long 
>> ago and the age of 32bit processors is ending.
> 
> No it isn't. I doubt very much that use of 32-bit processors is going 
> away any time soon. (In "traditional desktops", maybe, but not embedded 
> devices. Perhaps even in devices Fedora is interested in supporting, but 
> that I'm not so sure about. It will depend heavily on a: if netbooks 
> universally switch to 64-bit CPU's, and b: if Fedora decides to support 
> other sorts of MID's, e.g. "phones". Yes, I know, at the point Fedora is 
> running on such a device it will be "an MID that happens to be able to 
> make phone calls", but we're already at that stage.)
> 
> And I hear plenty of embedded devices still use *16*-bit CPU's...

Ok, I should probably a bit more precise: 32 bit being default on 64 bit 
capable computers is coming to an end as the default RAM size for desktops 
goes beyond 4GB. Real 32 bit or even 16 bit processors are completely 
unaffected by any multilib considerations anyway.

>> There are several annoying features
>> of the solution that was chosen at the time (overwriting 32 bit binaries,
>> install lots of files twice) and we should get rid of them at some 
>> point in
>> the (not too near) future. But this may require some other changes 
>> first...
> 
> Other than perhaps binutils, why would you ever have a 32-bit binary on 
> a 64-bit system? ;-) Or do you include libs in "binaries"?

There are several reasons to do so: Third party software that is not build
for 64 bit, software like firefox that uses plugins that are only available
in 32 bit, building software or content for 32 bit and may be some more.

When multilib was introduced 64 bit (x86) processors were new, shiny, 
expensive and
surrounded by 32 bit machines. So chances that you had to deal with 32 bit
software were very high at that time.

> As for the rest, IMO as long as gcc supports -m32, it should stay. The 
> project I work on for my day job would have to completely scrap our 
> build system and break what is currently a one-package multilib 
> distribution into two separate platforms, if multilib went away.

Multilib is not going to go away in the sense that you still will be able to 
32 bit software on a 64 bit installation. But it already got away in the 
sense that we do no longer install 32 bit libs by default. There is still 
some painful implementation details that I hope we can fix in a medium time 
frame.

Florian