Fedora -> Fedora cross binutils/gcc/gdb packages

[Lennert Buytenhek]

Hi,

I've uploaded a set of prebuilt Fedora -> Fedora cross
binutils/gcc/gdb packages (and their corresponding spec diffs[*]) to:

	http://ftp.linux.org.uk/pub/linux/arm/fedora/cross/latest/

Currently, only i386 -> arm and x86_64 -> arm binary RPMS are
provided.  Non-arm target architectures aren't tested, but should
be possible to make work without too much effort.

These RPMS can be used to cross-compile kernels, and to
cross-compile binaries that are to be run on Fedora systems -- i.e.,
built binaries are built against glibc (so, you can't use these RPMS
to build uClibc binaries, for example) and against other libraries as
included in Fedora.

These RPMS expect a couple of target libraries such as glibc to be
installed in the standard sysroot location, /usr/$target/sys-root/.
There is a script called repack_cross.pl which can convert a target
binary RPM to a noarch RPM with all files moved to
/usr/$target/sys-root/, and a set of such pre-generated noarch RPMS
is included in the abovementioned repository (and pulled in when
you install the cross-compiler.)

There is no support for building the required target libraries without
building the compiler first.  In other words, since the build process
for the cross-compiler depends on there being a suitable target glibc
already, these RPMS and spec diffs can not be used to bootstrap a new
Fedora architecture port from scratch.

Feedback appreciated.


cheers,
Lennert


[*] The included cross-binutils patch is based on an earlier
    cross-binutils patch by David Woodhouse.

[Roland McGrath]

>  There is a script called repack_cross.pl which can convert a target
>  binary RPM to a noarch RPM with all files moved to
>  /usr/$target/sys-root/, and a set of such pre-generated noarch RPMS
>  is included in the abovementioned repository (and pulled in when
>  you install the cross-compiler.) 
Is there a benefit to this approach vs rpm --root /usr/$target/sys-root
or something along those lines?  It would be nice if all you needed were:
  yum --installroot=/usr/$target/sys-root --arch=$arch groupinstall Development


Thanks,
Roland

[Lennert Buytenhek]

On Mon, Oct 01, 2007 at 07:25:37PM -0700, Roland McGrath wrote:

>  > There is a script called repack_cross.pl which can convert a
> target
>  > binary RPM to a noarch RPM with all files moved to
>  > /usr/$target/sys-root/, and a set of such pre-generated noarch RPMS
>  > is included in the abovementioned repository (and pulled in when
>  > you install the cross-compiler.)
>  
>  Is there a benefit to this approach vs rpm --root /usr/$target/sys-root
>  or something along those lines?  It would be nice if all you needed were:
>    yum --installroot=/usr/$target/sys-root --arch=$arch groupinstall Development 
In your approach, the sys-root would have its own rpm database, which
would make expressing target (build) dependencies somewhat harder,
since rpm wouldn't be able to query the set of installed target rpms.

In my approach target deps are specified by saying something like
"BuildRequires: foo-%{target_triple}".  It would be nice if you could
say something like this instead:

	BuildRequires(target): foo

and if rpm would then know it should query the rpm database in the
sysroot.

[Ralf Corsepius]

On Mon, 2007-10-01 at 19:25 -0700, Roland McGrath wrote:
>  > There is a script called repack_cross.pl which can convert a
> target
>  > binary RPM to a noarch RPM with all files moved to
>  > /usr/$target/sys-root/, and a set of such pre-generated noarch RPMS
>  > is included in the abovementioned repository (and pulled in when
>  > you install the cross-compiler.)
>  
>  Is there a benefit to this approach vs rpm --root /usr/$target/sys-root
>  or something along those lines? 
The "rpm --root" approach is not applicable to cross toolchains, because
cross tools are native host binaries and produce binaries for a target.

The "rpm --root" approach would be applicable to set up a
cross-toolchain's target environment (i.e. the target environment being
_used_ by a cross-toolchain)

Ralf

[Lennert Buytenhek]

On Tue, Oct 02, 2007 at 04:46:17AM +0200, Ralf Corsepius wrote:

>  > > There is a script called repack_cross.pl which can convert
> a target
>  > > binary RPM to a noarch RPM with all files moved to
>  > > /usr/$target/sys-root/, and a set of such pre-generated noarch RPMS
>  > > is included in the abovementioned repository (and pulled in when
>  > > you install the cross-compiler.)
>  > 
>  > Is there a benefit to this approach vs rpm --root /usr/$target/sys-root
>  > or something along those lines?
>  
>  The "rpm --root" approach is not applicable to cross toolchains, because
>  cross tools are native host binaries and produce binaries for a target.
>  
>  The "rpm --root" approach would be applicable to set up a
>  cross-toolchain's target environment (i.e. the target environment being
>  _used_ by a cross-toolchain) 
He was talking about that latter case, though.

I.e., what you put into /usr/$target/sys-root _are_ target packages.