[Buildroot] [PATCH v4 1/2] arch: add BR2_READELF_ARCH_NAME hidden config option

Arnout Vandecappelle arnout at mind.be
Mon Apr 10 15:49:42 UTC 2017



On 03-04-17 17:08, Thomas Petazzoni wrote:
> Hello,
> 
> On Mon, 3 Apr 2017 16:24:55 +0200, Arnout Vandecappelle wrote:
> 
>>  So, let me get this clear: libmpeg2 actually does the right thing, and it is in
>> fact possible to link the Sparc v8+ library with Sparc libraries?
> 
> It's not so much that you can link Sparc v8+ code with Sparc code that
> is important:  you can link ARMv5 and ARMv7 code together, but running
> ARMv7 code on ARMv5 still doesn't make sense.
> 
> And "Sparc v8+" on regular Sparc like we support is not going to work.
> However, what is important here is that libmpeg is smart enough to not
> call into the Sparc v8+ code if we're not on Sparc v8+.
> 
> It's exactly like having SSE3 code built-in, and testing at runtime if
> SSE3 is enabled before calling the SSE3 specific code. In a Buildroot
> context where we normally build for specifically the target system,
> this shouldn't be necessary, but some software packages do this anyway.
> 
>>  In that case, I guess we should extend check-bin-arch to support regexes for
>> the expected arch, and set the BR2_sparc arch to "Sparc( v8+)?".
> 
> Not as simple: another package may generate Sparc v8+ code, and this
> would be bogus.
> 
> So, in the context of Buildroot, I believe we should rather patch
> libmpeg to not generate the Sparc v8+ code if we are not on Sparc v8+.

 That is an option. But perhaps it's better to add a possibility for a
per-package exclusion of a file that is checked manually. I'll see if I can cook
something up.

 Regards,
 Arnout

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
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