On Fri, 2008-07-11 at 11:47 +0200, Hans de Goede wrote: > Hi all, > > I know bugzilla is my friend and I will put this in bugzilla, but I believe > this needs many eyes, so hence I'm first discussing it here. > > Currently when building rpms on an i686 and using %configure in your specfile > rpmbuild calls configure like this (non interesting stuff removed): > ./configure --build=i686-pc-linux-gnu --host=i686-pc-linux-gnu \ > --target=i386-redhat-linux-gnu > > This is just plain wrong, this should be: > ./configure --build=i686-pc-linux-gnu --host=i386-redhat-linux-gnu \ > --target=i386-redhat-linux-gnu Both are wrong. Both use the wrong target The latter is worse: it trigger cross-compilation mode, because build != host. > Or preferable just: > ./configure --build=i686-pc-linux-gnu --host=i386-redhat-linux-gnu Preferable is ./configure, because then build and host will be autodetected. > Here is a chapter of the autotools book describing the meaning of --build > --target and --host: > http://www.ensta.fr/~diam/dev/online/autoconf/autobook/autobook_259.html > > > Normally one only needs to specify build and host: > --build specifies the canonical name of the system on which the packages is > build > --host specifies the canonical name of the system on which the packages will > run > > So clearly specifying a host of i686-pc-linux-gnu for .i386 rpms is wrong, Once more: no. The target-tuples actually specify the name of the canonicalized toolchain. I.e. configure scripts will pick up i686-pc-linux-gnu-gcc and set CC to it if --host=i686-pc-linux-gnu is given and if build != host. Whether this CC generates i386 or i686 is a matter of the CFLAGS being passed to the CC. However, I agree. Using i686-* as target tuple isn't necessarily a wise decision. > An example to hopefully make things clearer, lets say I'm building gcc on an > i686 and I want to run the resulting gcc binaries on a powerpc using Fedora, > and I want the gcc binaries to generate code for an arm, then I would specify: > ./configure --build=i686-pc-linux-gnu --host=powerpc-redhat-linux-gnu \ > --target=arm-redhat-linux-gnu > > (Yes that would be cross compiling a cross compiler). It would not be simple cross-compilation. Your example is a case of Canadian cross-compilation. It's one magnitude more difficult. > As said the correct invocation of ./configure on an i686 to build .i386 rpms > would be: > ./configure --build=i686-pc-linux-gnu --host=i386-redhat-linux-gnu No. > There is one problem here though, now the --build and --host strings are not > equal, so autoconf will assume we're cross-compiling which isn't really true. Correct. Your proposal triggers cross-compilation. > A solution for this would be to invoke configure like this: > ./configure --build=i386-redhat-linux-gnu --host=i386-redhat-linux-gnu Correct. This would not trigger cross-compilation. Ralf -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
