RPI2, www/firefox, error: "NEON support not enabled"

[Mark Millard]

On 2017-May-5, at 4:01 PM, bob prohaska <fbsd at www.zefox.net> wrote:

> On Fri, May 05, 2017 at 12:38:14PM -0700, Mark Millard wrote:
>> 
>> An rpi2 has Cortex-A7 (armv7-A) cores that have NEON
>> but armv6 does not.
>> 
>> There is some possibility that with something like
>> -mcpu=cortex-a7 in use as a compiler option that
>> NEON would be used.
> 
> What's the simplest way to try it on a self-hosted RPI2 running
> -current? At this point I'm just using make -DBATCH in
> /usr/ports/www/firefox and following my nose.  There's nothing 
> valuable on the system, it's only for testing.

I've never built firefox for anything. The only place I
have set up a (fairly minimal) x11 environment is on
amd64 virtual machine guests, again no firefox or
anything else major, just lumina and xterm (local use,
not internet use).

So it would be a research project for me to get a
special/non-default firefox build done on a rpi2.

(There are some fairly general, but not universal,
techniques for supplying compiler options to ports.
I've no clue were firefox lands for such
properties.)

>> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=217611
>> 
>> (VFP and NEON are related by the registers used.)
>> 
>> So there could be other problems with NEON enabled code
>> until it is all resolved. (And head gets the work before
>> stable/11 gets the result.)
>> 
> 
> Most of the discussion in the thread is beyond me, but it
> is appreciated that the problem isn't simple.

The overall effect: you may get odd results from
corrupted NEON register values when NEON is put
to use. (I do not know the detailed status of what
is working vs. not for NEON/VFP at this point.)

===
Mark Millard
markmi at dsl-only.net