AMD64 Linux documentation

[Bryan O'Sullivan]

On Thu, 2003-12-11 at 13:07, Gene C. wrote:

> I am especially interested in how it supports 
> both 32 bit and 64 bit applications and how the file system (and other stuff) 
> will be configured to handle both 32 bit and 64 bit applications.

32-bit shared libraries live in /usr/lib and /lib; 64-bit libraries live
in /usr/lib64 and so on.  Binaries all install to the usual directories
regardless of which architecture they are.

>   It might 
> also be nice to be able to have both 32 bit and 64 bit versions of some 
> applications installed at the same time (e.g., mozilla).

You'd have to build separate RPMs for that.

> I also took a quick look at both SUSE and Mandrake but the most I could find 
> was some pitches for selling their AMD64 version which will be available RSN.

Both vendors have had AMD64 distros available for a while.  SuSE was
responsible for porting Linux to AMD64 in the first place, so they did
all the "grunt work".

> However, there are still conflicts 
> with between the 32 bit and 64 bit version of glibc (for example) -- 
> /usr/share/doc, /usr/sbin/ sbin/ and /etc which would (not easily) allow 
> concurrent installation.  

There's a hack in place in the latest Red Hat version of RPM that
basically chooses 64-bit binaries in preference to 32-bit binaries when
there's a conflict.  This hack seems to apply to docs, too, but not to
some other kinds of files such as scripts.  The result is that many
packages (glibc being one) can cleanly have 32-bit and 64-bit packages
installed simultaneously, but others can't be installed bi-arch without
some crowbar work due to having inter-package dependencies that break
them (XFree86 was this way last time I checked).

> One of the great attractions of the AMD64 (at least to me) is the 
> ability to run "old" 32 bit applications at the same time (on the same 
> system) I am running 64 bit applications.

This works out well in practice for many applications, once you have the
base system installed properly and the ragged edges beaten into shape. 
I'm sure those ragged edges will get worked out over the next several
months.

	<b