Greetings fellow secondary arch folks,
As some of you might know, we are working to introduce a new architecture called ppc64le into Fedora. It's just as it sounds, ppc64 (64bit only) but little endian. We've been emulating the Fedora process as close as possible internally here and have quite a few packages built, including using things like mock and koji.
As with introducing any new architecture, one of the issues we are seeing is that current packages lack the libtool (config.guess|sub,m4) magic to recognize the architecture. While rpmbuild and mock do properly influence build and targets, the one area we still a high rate of failure with is when configure asks the linker if it supports shared libs. In our case, it actually asks the linker with the wrong architecture.
In an ideal situation, libtool would release a new version with the ppc64le content (which is already upstream with them) and ALL upstream maintainers would immediately add the new content and drop new releases. That's ideal but not realistic.
I also would prefer to NOT update every Fedora package/.spec with a patch to fix this and would prefer to have this be the rare exception rather than the rule.
So in the interest of beginning work in Fedora and not making a mess of things, I'd like to propose another alternative (and solicit more ideas as well). In extending the case where configure “asks” the linker if it supports shared libraries, it actually will pass an incorrect architecture. Using lcms2's configure as an example:
checking whether the gcc -std=gnu99 linker (/bin/ld -m elf64ppc) supports shared libraries... no
In our internal development here, we've patched the linker to always respond as if it was asked about the ppc64le architecture. This function is enabled as an environment variable (LD_FORCE_LE=1). We've been using this for several months and I have yet to encounter an instance where something bad happens.
So I'd like to propose that for initial Fedora ppc64le development, we enable this patch for the linker, at least for the first release. Meanwhile, we can identify and manage the list of packages that need updated libtool information on the side. We could then identify a good cutover point and disable the linker patch in a future release.
If this could be helpful for other new arches like aarch64, we could share the this patch as well.
I believe the Fedora PPC64 team is supportive of this (at least for the ppc64le arch) but we wanted to just solicit broader input.
Feedback appreciated,
Brent
Brent J. Baude Linux Technology Center 3605 Hwy 52N Rochester, MN 55901
http://www.ibm.com/linux/ltc/ 507.253-0708