Re: [dpdk-dev] [PATCH] build: use generic march on arm64 when using 'default' machine

[Luca Boccassi <bluca@debian.org>]

On Mon, 2019-01-07 at 12:24 +0000, Bruce Richardson wrote:
> On Mon, Dec 24, 2018 at 01:56:27PM +0100, Luca Boccassi wrote:
> > When building for generic distribution we need a stable baseline
> > architecture, or depending on the build worker the result will
> > vary.
> > 
> > Force the default flags if the user explicitly sets
> > marchine=default
> 
> typo: marchine
> 
> > at configuration time.
> > 
> > Fixes: b1d48c41189a ("build: support ARM with meson")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: Luca Boccassi <bluca@debian.org>
> > ---
> >  config/arm/meson.build | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/config/arm/meson.build b/config/arm/meson.build
> > index dae55d6b2..fa21a2fd2 100644
> > --- a/config/arm/meson.build
> > +++ b/config/arm/meson.build
> > @@ -6,6 +6,7 @@
> >  march_opt = '-march=@0@'.format(machine)
> >  
> >  arm_force_native_march = false
> > +arm_force_default_march = machine == 'default'
> 
> Do we need a new variable here? Given it only seems to be used once
> below,
> I think just having the boolean expression directly in the if
> statement is
> clearer. If you do keep the variable, suggest putting braces around
> the
> comparison, otherwise at first glance it looks like a chained
> assignment
> like you get in C e.g. x = y = 0;
> 
> >  
> >  machine_args_generic = [
> >  	['default', ['-march=armv8-a+crc+crypto']],
> > @@ -105,7 +106,11 @@ else
> >  	cmd_generic = ['generic', '', '', 'default', '']
> >  	cmd_output = cmd_generic # Set generic by default
> >  	machine_args = [] # Clear previous machine args
> > -	if not meson.is_cross_build()
> > +	if arm_force_default_march and not meson.is_cross_build()
> > +		machine = impl_generic
> > +		cmd_output = cmd_generic
> > +		impl_pn = 'default'
> > +	elif not meson.is_cross_build()
> >  		# The script returns ['Implementer', 'Variant',
> > 'Architecture',
> >  		# 'Primary Part number', 'Revision']
> >  		detect_vendor = find_program(join_paths(
> > -- 
> > 2.19.2
> > 
> 
> With these comments, looks ok to me from a meson viewpoint. I think
> an ack
> from the arm side would be good to get too though.
> 
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>

Fixed typo, removed variable and added the arm maintainers to CC in v2,
thanks.

-- 
Kind regards,
Luca Boccassi