[fedora-arm] Setting host system type on ARMv5

[Peter Robinson]

On Mon, Jul 30, 2012 at 2:53 PM, David A. Marlin <dmarlin at redhat.com> wrote:
> Jon Masters wrote:
>>
>> On 07/30/2012 03:13 AM, Peter Robinson wrote:
>>
>>>
>>> On Mon, Jul 30, 2012 at 5:23 AM, Jon Masters <jonathan at jonmasters.org>
>>> wrote:
>>>
>>>>
>>>> Folks,
>>>>
>>>> In general, we probably want to look at the value of host system type
>>>> being picked up for ARMv5 builds, especially on ARMv7 builder systems.
>>>> Here's an example output from running an OpenMPI build on Fedora 18
>>>> using the current Koji builder setup, note the "armv7l" target:
>>>>
>>>> --- begin quote ---
>>>> checking build system type... armv7l-unknown-linux-gnueabi
>>>> checking host system type... armv7l-unknown-linux-gnueabi
>>>> checking target system type... armv7l-unknown-linux-gnueabi
>>>> --- end quote ---
>>>>
>>>> I believe that this is incorrect, at least, this is in question. The
>>>> compiler options (set elsewhere) are correct from an ABI point of view,
>>>> and the output will be a soft float ABI target, but it's not the right
>>>> architecture revision target. It will matter in a few cases. For example
>>>> when a package is choosing inline assembly or other specifics that
>>>> differ between ARMv5 and ARMv7. Mostly, we've been lucky in that the
>>>> differences are small, but I suspect hidden breakage is lurking.
>>>>
>>>> In this specific example, OpenMPI should move to the new GCC atomics
>>>> stuff in due course, but they have a giant mess called "asmlib" that
>>>> provides their own custom atomic functions (what could go wrong?) for
>>>> historical reasons. The macros used to build that are enough to make you
>>>> gouge your eyes out, but once you figure it out, it's obvious that they
>>>> do already have ARMv5 assembly code that should work, if it thinks it's
>>>> building for an armv5l system. And it's faster to just pick that up than
>>>> reworking a lot of not just code, but also other arches and build
>>>> macros, and other stuff unique to the OpenMPI atomics setup.
>>>>
>>>> Let's ponder how we're going to fix it. I could be wrong, but I'd think
>>>> we want to ensure that configure is picking up
>>>> armv5l-redhat-linux-gnueabi as the host type on armv5tel builds. It
>>>> should do this irrespective of the actual host architecture of the
>>>> builder. I tried just force overriding it in a test build with an
>>>> "%{ifarch} armv5tel" but that wasn't picked up, so I missed something,
>>>> but in general that's not the right approach anyway. We want something
>>>> at the r-r-c level.
>>>>
>>>> Comments? Dennis? Peter?
>>>>
>>>
>>> It should always take the details that the build system is telling it
>>> and not the underlying platform without exception. The same goes with
>>> features like NEON (and MMX/SSE on x86). I've fixed a number of these
>>> before.
>>>
>>
>>
>> Good. Then you agree it should be thinking armv5l-redhat-linux-gnueabi
>> there and this is a bug we need to fix.
>
> Just for clarification, are you saying that something is not being set
> correctly (in rpmmacros, etc.) in the v5 mock chroot when v5 builds are
> being run on a v7 host?

No, some projects aren't following the cflags etc as specified in rpmmacros.

Peter