Re: Testsuite failures on sparc64 due to unaligned access since 1.5.0

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On Fri, Dec 11, 2020 at 03:14:26PM +0100, John Paul Adrian Glaubitz wrote:
> Hi!
> On 12/11/20 2:07 AM, David Gibson wrote:
> > Right, alignment issues have been a perennial problem.  We find some
> > platform that has alignment constraints that break, fix that, then
> > someone finds the alignment fixups cause horrible performance
> > problems, repeat ad nauseum.
> From my discussions with GCC developers I have learnt that it shouldn't
> be a problem to use memcpy() in such cases to avoid aliasing problems
> resulting in unaligned access.
> GCC will just optimize memcpy() in cases where an unaligned access is
> faster.
> > There's been another round of this pretty recently, which is probably
> > the cause of the fixup.  I just hope the re-optimizations that Tom
> > Rini has in his pipeline don't break things again for you.
> The GCC compile farm has two fast SPARC servers [1] running Debian unstable,
> so I suggest testing such changes there before merging them.

It's just restoring the historical behavior, and Rob was just saying
this was a change in dtc and not libfdt, so should be fine.  I sent out
v3 last night, but I don't see it in the archives yet, if I sent it to
you directly would you be able to give it a quick spin?  Thanks!


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