AMD64 Linux documentation

Justin M. Forbes 64bit_fedora at comcast.net
Thu Dec 11 22:10:50 UTC 2003


On Thu, Dec 11, 2003 at 04:07:14PM -0500, Gene C. wrote:
> Is there any documentation available for the AMD64 version of Fedora Core (or 
> RHEL for that matter)?  Yes, I have read the FAQ.
> 
At this point, documentation is lagging, but should be updated before an
actual gold release of Fedora Core for AMD64.  I have been spending most of
my time tracking down bugs and testing, instead of documenting.  With a day
job, and family, I have to do what I can in the time I have.  That said I
will try to answer some of your questions here.

> 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.  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).
> 
Currently, all applications are 64bit with the following noted exceptions:
- Open Office.org is 32bit only, and will remain so until some of the code
  is changed.  It still functions quite well in my testing.

- Mozilla, originally was installed both 64bit and 32bit, but that may
  change before test1 release, with the removal of 64bit.  32bit is
  required for Open Office.org, and 32bit plugins (many of which are not open
  source or available 64bit yet) will not work in 64bit unless someone takes
  the time to write a thunking layer.  As a result, epiphany must go 32bit as
  well.

Libraries are a different issue, and libtool handles the 64bit/32bit
concurrent install deal.  32bit libraries are provided to support many of
the majr apps, and I have 32bit Java/flash player, and mp3 support running
on my system just fine.  32bit libs which are not required by the above
mentioned 32bit apps, and which are not in extremely high use by apps which
I would expect people to use 32bit still are not going to be included in
the distribution because if they are not wideley tested, we cannot
guarantee their funtionality. That said, there is no voodoo required for
installation of most libs anyway.

In the kernel, the required 32bit syscalls should be implemented, and I
will be glad to look at any which seem to be missing.
 
> The only thing I could find on debian is a 
> short HOWTO which basically comes down to ... install a 32 bit system and 
> then install a 64 bit kernel but do not install any 64 bit application 
> because they are not "stable".  Since Red Hat is marketing (and delivering) 
> RHEL 3 for the AMD64/Opteron, I suspect they have worked out a lot of 
> stability problems (through a lot of blood, sweat and tears on their part).
> 
Actually 64bit seems to work well in most cases, which is why we are
looking at a mostly 64bit system here (With the above noted exceptions).
  
> I also did some browsing of the packages available in the preview version.  
> From what I could see there are a couple of new directory trees such as 
> /lib64 and /usr/lib64 which hold the 64 bit versions of libraries with the 32 
> bit version going into /lib and /usr/lib.  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.  I took a look at some of the packages in 
> taroon-amd64 and the same thing is true there.
> 

We are looking to resolve any conflicts where they exist.  Note that
/usr/share/doc and often times /etc does not necessarily mean conflict.  If
the files are the exact same, then there is no conflict, and every package
has what it installed.  That said there are a few issues being addressed
which is one of the reasons we are still in a preview release and not a
full test1.
 
> I realize that this (Fedora Core for the AMD64) is a "work in progress" but I 
> am hoping for some information as to how these this will (are being) made to 
> work.  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.  The AMD64 is very different from 
> the Itanium since I do not need to port and rebuild my 32 bit application ... 
> the only other hardware I am aware that has this dual mode (32 bit/64 bit) 
> capability is the Sun Sparc.
> 
32bit compatability is a strong feature of this platform, we are looking to
keep that.

> OK, I am hoping that some of the folks at Red Hat (and perhaps others) have 
> given this some thought and have a strategy for this.

It is being thought, and addressed.  Any feedback, recommendations, or
patches are definately appreciated.

Justin M. Forbes





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