Re: [Devil-linux-develop] Suggestion for better compiling.

[Bruce S. <bw...@ar...>]

> > We could find out for sure if there was some way to determine what arch
> > a pre-compiled binary was compiled for.  (I could check my i686 compiled
> > DL and see).  Except I don't know of any way to tell.  Does anyone know
> > of a way to tell?
> 
> 	I thought that using readelf would do it but it's displaying the same
> machine info for DL compiled binaries for a 486 and binaries compiled on
> my Mandrake which is compiled for i586.
> 
> 	If you do a readelf -a <binary name> you'll see at the very top of the
> listing elf header information.  One of the lines has.
> 
> "Machine : Intel 80386"
> 
> I would assume that this is where the -march=???? should go but doesn't
> appear to. It's always 80386.

Yes, that doesn't work.   I tried it on the same program I compiled two
different ways.  It displays the same for both.

I suppose we could specifically compile one with -march=i686 and again
without any -march options, and compare the two binaries.

> > For some applications it would make no difference.  But it can make a
> > big difference for some packages.  For example almost all programs use
> > glibc extensively, so it will help a lot there.  And it can help
> > stand-alone programs which are CPU intensive, like OpenSSL.
> > 
> > We could go through and modify the few packages it would help and forget
> > the rest (like Redhat does on their distribution).  Or do everything.
> > 
> 	I agree that it would affect some applications. If we do some packages
> then when lets keep in mind that one day all of them would be done too..
> Obviously starting with the packages that would have the most affect,
> can you think of any others packages other then glibc and openssl?

I used those two as examples because Redhat supplies multiple arch's for
those RPM's.

I suppose anything that does encryption or a lot of math could use it. 
OpenSSH, all the VPN packages, gnupg, ...

 - BS