OpenSSL -mcpu flag

Jörg W Mittag Joerg.Mittag at Web.De
Thu Dec 9 15:54:05 PST 2004

Thomas Trepl wrote:
> Jörg W Mittag wrote:
>> Igor Zivkovic wrote:
>>> Thomas Trepl wrote:
>>>>   sed -i "s/-mcpu=/-march=/g" ./Configure
>>> Unnecessary maintenance.
>> And wrong, too. -mcpu has been replaced by -mtune, not by -march. -march
>> and -mcpu/-mtune have different semantics.
> The message gcc show says:
>   `-mcpu=' is deprecated. Use `-mtune=' or '-march=' instead.
> So how to interpret this? Doesn't it say that -mtune *or* -march are
> alternatives for -mcpu?

-mcpu is a deprecated synonym for -mtune, so both have identical semantics.
-march has different semantics, but it implies -mtune/-mcpu. So, -march does
the same things as -mtune does *and more*. That means that, yes, in some
cases depending on what you actually want to achieve -march might be able to
serve as a replacement for -mcpu. However, this needs to be decided at a
case by case basis and is shurely not advisable for an unconditional sed

Just as an example for those semantic differences: software compiled with
-mtune=pentium4 will run on an 80386, software compiled with -march=pentium4
will not.

gtkmm-1.2.10% ./configure --help
  --enable-voodoo    Use Voodoo Fried Chicken spell to compile Gtk--
      (use this only when everything else fails)

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