[U-Boot] [PATCH] arm: enable unaligned access on ARMv7

Albert ARIBAUD
2012-06-22T11:16:54Z

Hi Lucas,

> > > Linux in particular does reinitialize this state and I expect any
> > > reasonable OS to do so.
> >
> > Then what is the point of enabling it on U-Boot? Does it fix some
> > issue whereby some mis-aligned piece of data cannot be properly
> > aligned?
> >
> Yes, it fixes U-Boot USB on Tegra, when built with a recent toolchain.
> Fixing the alignment of some of the structures in the USB code should
> also be done, but this is a whole lot more invasive and requires some
> more thought, as the discussion about this on LKML shows. The issue
> doesn't show for older toolchains, as they by default emit code to
> work around unaligned accesses.
>
> This patch fixes all unaligned issues, that may appear with recent
> toolchains. We avoid having to instruct the toolchain to work around
> unaligned accesses and gain better performance in cases where it is
> needed.

I am not too happy with enabling a lax behavior only to avoid an
issue which apparently is diagnosed and could / should be fixed at
its root. Can you point me to the relevant LKML thread
so that I get the details and understand what prevents fixing this by
'simply' aligning the USB structures?

> Thanks,
> Lucas

Amicalement,
--
Albert.