SlackBuild / ./configure questions

elyk · 10-03-2005, 05:13 PM

The -march and -mcpu settings will tell the compiler to optimize for a specific processor, or to generate instructions that a certain processor will be able to run.

What do the --build, --host, and --target settings actually do? I understand the compiler flags, but not the configure script flags.

egag · 10-03-2005, 05:37 PM

as i understand it, you only need to set the " build " option.
( i486-slackware-linux in our case )

those binaries will also run on a mandrake-linux box.
i have ( or had ? ) some programs running here, that came in a(n) rpm package
and they run ok.
so the other way around will also work.

the " host " and " target " options are only used for cross compiling
( to make a binary for another processor lika a sparc )

maybe this will clear some things up :
http://linux.bytesex.org/cross-compiler.html
( there is an example of the " target " option )

egag

win32sux · 10-03-2005, 05:39 PM

Quote:

Originally posted by shilo
I would think that you would use:

Code:

./configure --build=i586-mandrake-linux \ --host=i486-slackware-linux \ --target=i586-mandrake-linux

And you would also have to have the i586-mandrake-linux libraries installed on the Slackware machine.

Is this not correct?

actually, i would think it's:

Code:

./configure --build=i486-slackware-linux \
  --host=i586-mandrake-linux \
  --target=i586-mandrake-linux

and then you'd compile it with:

Code:

CFLAGS="-O2 -march=i586 -mcpu=i686"

no??

Quote:

To compile a program to run on a host type that differs from the build type, use the configure option --host=hosttype, where hosttype uses the same syntax as buildtype. The host type normally defaults to the build type.

PS: also, i would think that you wouldn't need to have the i586-mandrake-linux libraries in order to do this, but i'm not sure...

elyk · 10-04-2005, 02:29 AM

I found these symlinks in /usr/bin

Code:

lrwxrwxrwx  1 root root 13 2005-09-17 08:22 i486-slackware-linux-c++ -> g++-gcc-3.3.6*
lrwxrwxrwx  1 root root 13 2005-09-17 08:22 i486-slackware-linux-g++ -> g++-gcc-3.3.6*
lrwxrwxrwx  1 root root  9 2005-09-17 08:22 i486-slackware-linux-gcc -> gcc-3.3.6*
lrwxrwxrwx  1 root root  9 2005-09-17 08:22 i486-slackware-linux-gcc-3.3.6 -> gcc-3.3.6*
lrwxrwxrwx  1 root root  3 2005-09-17 08:22 i486-slackware-linux-gcj -> gcj*

If I understand correctly, build/host/target will select your compiler and march/mcpu will optimize what that compiler creates.