[U-Boot] [PATCH v4 4/6] armv7: Use -march=armv7-a and thereby enable Thumb-2

[Albert ARIBAUD]

Hi Marek,

On Sat, 7 Jul 2012 09:59:52 +0200, Marek Vasut <marek.vasut at gmail.com> wrote:
> Dear Aneesh V,
> 
> > Hi Marek,
> > 
> > On 07/06/2012 04:32 PM, Tetsuyuki Kobayashi wrote:
> > > Hello,
> > > 
> > > On 2012/07/07, at 8:02, Marek Vasut wrote:
> > >> Dear Aneesh V,
> > >> 
> > >>> Enable -march=armv7-a for armv7 platforms if the tool-chain
> > >>> supports it. This in turn results in Thumb-2 code generated
> > >>> for these platforms if CONFIG_SYS_THUMB_BUILD is enabled.
> > >>> 
> > >>> Signed-off-by: Aneesh V<aneesh at ti.com>
> > >>> ---
> > >> 
> > >> For some reason, this patch breaks USB EHCI on mx51 efika boards. The
> > >> board just freezes instead of detecting USB devices. Reverting this
> > >> patch fixes the issue.
> > >> 
> > >> Note I use gcc 4.7.1 (!), might be compiler issue?
> > >> 
> > >> Tom, can you try on one of your beagle-dogs please? :)
> > > 
> > > Just for your information,
> > > I doubt unaligned access causes this problem.
> > > 
> > > My investigation is here,
> > > http://lists.denx.de/pipermail/u-boot/2012-June/127020.html
> > > My patch
> > > [PATCH] arm: armv7: add compile option	-mno-unaligned-access if 
> available
> > > http://lists.denx.de/pipermail/u-boot/2012-July/127260.html
> > 
> > This makes sense. You might want to try this patch. Also, to be sure
> > that it's nothing to do with Thumb you can make sure you are not
> > enabling CONFIG_SYS_THUMB_BUILD.
> 
> Ok, I think the patch should be applied then ?
> 
> but what if the option isn't available?

If I am not mistaken, from an analysis standpoint, on compilers where the
option is unavailable, there is no issue regarding alignment; and from a
solution standpoint... We'll need to add the option only when cross-compiler
version is known to honor it.

> Best regards,
> Marek Vasut

Amicalement,
-- 
Albert.