embed endian info in locale data files magic (PR231965)

[Brooks Davis]

On Thu, Oct 18, 2018 at 09:57:29AM +0200, Baptiste Daroussin wrote:
> On Thu, Oct 18, 2018 at 04:58:58AM +0300, Yuri Pankov wrote:
> > Yuri Pankov wrote:
> > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=231965 ([PowerPC64]
> > > Cross compiling powerpc64 from amd64 results in nonfunctional locale
> > > installations), describes the issue with locale data built on LE system
> > > (amd64) when used on BE system (powerpc).
> > > 
> > > Fix introduced in rS308170 depends on the fact that locale data is built
> > > on LE system, and will likely fail when it's built natively on mips
> > > (please correct me if I'm wrong).  More so, we shouldn't be hardcoding
> > > the conversion in libc, and I see 2 options here:
> > > 
> > > 1. fix localedef to output data in target's system endian
> > > 2. embed the endian info in locale data files (updating magic signature)
> > >    and ehhance the previous fix with runtime selection of needed
> > >    conversion
> > 
> > Thinking more about this, or:
> > 
> > 3. Always store the data in LE (or BE, doesn't matter), and
> > appropriately convert while reading.  This will likely require least change.
> > 
> I agree on that approach, just some benchmarking would be needed to make sure
> we are not killing the performance

While not a bad idea, we should probably focus on benchmarking modern
power systems.  None of the other BE systems are all that important IMO
(I say this as someone who uses BE mips64 daily.)

-- Brooks
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