[Buildroot] [PATCH] package/libnss: fix build failure due to HW PPC Crypto bug

[Yann E. MORIN <yann.morin.1998@free.fr>]

Giulio, Vincent, All,

On 2020-01-01 00:44 +0100, Giulio Benetti spake thusly:
> On 1/1/20 12:31 AM, Vincent Fazio wrote:
> >On 12/31/19 4:49 PM, Vincent Fazio wrote:
[--SNIP--]
> >> ??????? /* clang needs the following cast away from const; maybe a bug
> >>in 7.0.0 */
> >> ??????? v = (vec_u64)vec_xl_be(0, (unsigned char *)buf);
> >>
> >>It should be fine to call endian specific functions if you know how
> >>the data is stored.
[--SNIP--]
> >>Based on the below commit, it was tested on a POWER8, presumably in LE
> >>mode, so I'd be hesitant to switch any endian checks:
> >>https://hg.mozilla.org/projects/nss/rev/3d7e509d6d20ecd607a28fa6ce42e4ffd9c51443
[--SNIP--]
> >>The bigger issue may be that 'vec_xl_be' wasn't introduced until GCC 8
> >>and the toolchain used in the failed build is GCC 7, so that function
> >>is not available in altivec.h:
> >>https://github.com/gcc-mirror/gcc/commit/f7b0548e5eba54b637977e3df4d4daf0cabe474d

Thanks Vincent for digging all this info, very informative. :-)

> ...this is a good idea. So with gcc version < 8.x let's disable
> USE_PPC_CRYPTO and with gcc version >= 8.x let's enable it only if
> LITTLE_ENDIAN. So at this point I would change my upstream patch to do that
> in NSS, since there's already a gcc version check but only against version
> 5.x(>=) that instead needs to be >= 8.x.

Yes, that sounds like a good plan. I've marked this patch as changes
requested in ptachwork in the meantime.

Thanks! :-)

Regards,
Yann E. MORIN.

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