Re: [dpdk-dev] [PATCH v8 01/14] build: alias default build as generic

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

<snip>

> > >
> > > The current machine='default' build name is not descriptive. The
> > > actual default build is machine='native'. Add an alternative string
> > > which does the same build and better describes what we're building:
> > > machine='generic'. Leave machine='default' for backwards compatibility.
> > >
> > > Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
> > > ---
> > >  config/arm/meson.build                    | 5 +++--
> > >  config/meson.build                        | 9 +++++----
> > >  doc/guides/prog_guide/build-sdk-meson.rst | 4 ++--
> > >  meson_options.txt                         | 2 +-
> > >  4 files changed, 11 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/config/arm/meson.build b/config/arm/meson.build index
> > > 42b4e43c7..d4066ade8 100644
> > > --- a/config/arm/meson.build
> > > +++ b/config/arm/meson.build
> > > @@ -1,12 +1,13 @@
> > >  # SPDX-License-Identifier: BSD-3-Clause  # Copyright(c) 2017 Intel
> > > Corporation.
> > >  # Copyright(c) 2017 Cavium, Inc
> > > +# Copyright(c) 2020 PANTHEON.tech s.r.o.
> > >
> > >  # for checking defines we need to use the correct compiler flags
> > > march_opt =
> > > '-march=@0@'.format(machine)
> > >
> > >  arm_force_native_march = false
> > > -arm_force_default_march = (machine == 'default')
> > > +arm_force_generic_march = (machine == 'generic')
> > >
> > >  flags_common_default = [
> > >  	# Accelarate rte_memcpy. Be sure to run unit test
> > > (memcpy_perf_autotest) @@ -148,7 +149,7 @@ else
> > >  	cmd_generic = ['generic', '', '', 'default', '']
> > >  	cmd_output = cmd_generic # Set generic by default
> > >  	machine_args = [] # Clear previous machine args
> > > -	if arm_force_default_march and not meson.is_cross_build()
> > > +	if arm_force_generic_march and not meson.is_cross_build()
> > >  		machine = impl_generic
> > >  		impl_pn = 'default'
> > >  	elif not meson.is_cross_build()
> > > diff --git a/config/meson.build b/config/meson.build index
> > > 258b01d06..c7f7aa6e2 100644
> > > --- a/config/meson.build
> > > +++ b/config/meson.build
> > > @@ -68,13 +68,14 @@ else
> > >  	machine = get_option('machine')
> > >  endif
> > >
> > > -# machine type 'default' is special, it defaults to the per arch
> > > agreed common -# minimal baseline needed for DPDK.
> > > +# machine type 'generic' is special, it defaults to the per arch
> > > +agreed common # minimal baseline needed for DPDK. Machine type
> > > +'default' is also supported # with the same meaning for backwards
> > compatibility.
> > >  # That might not be the most optimized, but the most portable
> > > version while # still being able to support the CPU features required for
> DPDK.
> > >  # This can be bumped up by the DPDK project, but it can never be an
> > > # invariant like 'native'
> > > -if machine == 'default'
> > > +if machine == 'default' or machine == 'generic'
> > >  	if host_machine.cpu_family().startswith('x86')
> > >  		# matches the old pre-meson build systems default
> > >  		machine = 'corei7'
> > > @@ -82,7 +83,7 @@ if machine == 'default'
> > >  		machine = 'armv7-a'
> > >  	elif host_machine.cpu_family().startswith('aarch')
> > >  		# arm64 manages defaults in config/arm/meson.build
> > > -		machine = 'default'
> > > +		machine = 'generic'
> > >  	elif host_machine.cpu_family().startswith('ppc')
> > >  		machine = 'power8'
> > >  	endif
> > > diff --git a/doc/guides/prog_guide/build-sdk-meson.rst
> > > b/doc/guides/prog_guide/build-sdk-meson.rst
> > > index 3429e2647..c7e12eedf 100644
> > > --- a/doc/guides/prog_guide/build-sdk-meson.rst
> > > +++ b/doc/guides/prog_guide/build-sdk-meson.rst
> > > @@ -85,7 +85,7 @@ Project-specific options are passed used -
> > > Doption=value::
> > >
> > >  	meson -Denable_docs=true fullbuild  # build and install docs
> > >
> > > -	meson -Dmachine=default  # use builder-independent baseline -
> > > march
> > > +	meson -Dmachine=generic  # use builder-independent baseline -
> > > march
> > >
> > >  	meson -Ddisable_drivers=event/*,net/tap  # disable tap driver and all
> > >  					# eventdev PMDs for a smaller build
> > @@ -114,7 +114,7 @@ Examples
> > > of setting some of the same options using meson configure::
> > >          re-scan from meson.
> > >
> > >  .. note::
> > > -        machine=default uses a config that works on all supported
> architectures
> > > +        machine=generic uses a config that works on all supported
> > > + architectures
> > >          regardless of the capabilities of the machine where the
> > > build is happening.
> > >
> > >  As well as those settings taken from ``meson configure``, other
> > > options diff -- git a/meson_options.txt b/meson_options.txt index
> > > 9bf18ab6b..ce23289e3
> > > 100644
> > > --- a/meson_options.txt
> > > +++ b/meson_options.txt
> > > @@ -23,7 +23,7 @@ option('kernel_dir', type: 'string', value: '',
> > > option('lib_musdk_dir', type: 'string', value: '',
> > >  	description: 'path to the MUSDK library installation directory')
> > > option('machine', type: 'string', value: 'native',
> > > -	description: 'set the target machine type')
> > > +	description: 'set the target machine type. Set to generic for a
> > > +build usable on most machines of the build machine architecture,
> > > +set to
> >                         ^^^^ all
> 
> I don't think we've settled this with Bruce. According to him, the build with
> "machine=generic" on x86 won't necessarily produce a build usable on all
> machines, so I went with most machines.
> 
> > > +native to let the compiler choose the best fit for the build
> > > +machine.')
> > How about: native to let the compiler choose the attributes of the
> > build machine
> >
> 
> I haven't looked at what the docs before, so now here's what GCC docs say:
> https://gcc.gnu.org/onlinedocs/gcc-8.4.0/gcc/AArch64-
> Options.html#AArch64-Options:
> The value ‘native’ is available on native AArch64 GNU/Linux and causes the
> compiler to pick the architecture of the host system.
> 
> Best fit is kinda vague and choosing the attibutes is probably not using the
> right verb (it's always going to use the same subset of attributes of the build
> machine in question, so it's not really a choice), I like use the attributes more.
> 
> So it would be either "use the attributes of the build machine" or "pick the
> architecture of the build machine" (I've changed host system to build machine
> to match meson language). Both look fine to be, but I'm always inclined to use
> wording from documentation, even if it's from one compiler. Which one do
> you like more?
I am fine with "pick the architecture of the build machine"

> 
> > Otherwise, it looks good to me.
> > Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> >
> > >  option('max_ethports', type: 'integer', value: 32,
> > >  	description: 'maximum number of Ethernet devices')
> > > option('max_lcores', type: 'integer', value: 128,
> > > --
> > > 2.20.1