build: remove architecture flag as default C flag

Any flags added to the project args are automatically added to all builds,
both native and cross-compiled. This is not what we want for the -march
flag as a valid -march for the cross-compile is not valid for pmdinfogen
which is a native-build tool.

Instead we store the march flag as a variable, and add it to the default
cflags for all libs, drivers, examples, etc. This will allow pmdinfogen to
compile successfully in a cross-compilation environment.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Luca Boccassi <bluca@debian.org>

app/test-pmd/meson.build

@@ -45,7 +45,7 @@ endif
 
 executable('dpdk-testpmd',
 	sources,
-	c_args: '-DALLOW_EXPERIMENTAL_API',
+	c_args: [machine_arg, '-DALLOW_EXPERIMENTAL_API'],
 	link_whole: link_libs,
 	dependencies: dep_objs,
 	install_rpath: join_paths(get_option('prefix'), driver_install_path),

buildtools/pmdinfogen/meson.build

@@ -6,5 +6,4 @@ pmdinfogen_inc += include_directories('../../lib/librte_pci')
 pmdinfogen = executable('pmdinfogen',
 	'pmdinfogen.c',
 	include_directories: pmdinfogen_inc,
-	native: true,
-	c_args: cflags)
+	native: true)

config/meson.build

@@ -2,9 +2,13 @@
 # Copyright(c) 2017 Intel Corporation
 
 # set the machine type and cflags for it
-machine = get_option('machine')
+if meson.is_cross_build()
+	machine = host_machine.cpu()
+else
+	machine = get_option('machine')
+endif
 dpdk_conf.set('RTE_MACHINE', machine)
-add_project_arguments('-march=@0@'.format(machine), language: 'c')
+machine_arg = '-march=' + machine
 
 # use pthreads
 add_project_link_arguments('-pthread', language: 'c')

doc/guides/contributing/coding_style.rst

@@ -800,7 +800,7 @@ build
 
 
 cflags
-	**Default Value = []**.
+	**Default Value = [<-march/-mcpu flags>]**.
 	Used to specify any additional cflags that need to be passed to compile
 	the sources in the library.
 

drivers/meson.build

@@ -23,7 +23,7 @@ foreach class:driver_classes
 		allow_experimental_apis = false
 		sources = []
 		objs = []
-		cflags = []
+		cflags = [machine_arg]
 		includes = [include_directories(drv_path)]
 		# set up internal deps. Drivers can append/override as necessary
 		deps = std_deps

drivers/net/i40e/meson.build

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright(c) 2017 Intel Corporation
 
-cflags = ['-DPF_DRIVER',
+cflags += ['-DPF_DRIVER',
 	'-DVF_DRIVER',
 	'-DINTEGRATED_VF',
 	'-DX722_A0_SUPPORT']

drivers/net/ixgbe/meson.build

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright(c) 2017 Intel Corporation
 
-cflags = ['-DRTE_LIBRTE_IXGBE_BYPASS']
+cflags += ['-DRTE_LIBRTE_IXGBE_BYPASS']
 
 subdir('base')
 objs = [base_objs]

examples/meson.build

@@ -10,7 +10,7 @@ foreach example: get_option('examples').split(',')
 	name = example
 	sources = []
 	allow_experimental_apis = false
-	cflags = []
+	cflags = [machine_arg]
 	ext_deps = []
 	includes = [include_directories(example)]
 	deps = ['eal', 'mempool', 'net', 'mbuf', 'ethdev', 'cmdline']

lib/meson.build

@@ -33,7 +33,7 @@ foreach l:libraries
 	sources = []
 	headers = []
 	includes = []
-	cflags = []
+	cflags = [machine_arg]
 	objs = [] # other object files to link against, used e.g. for
 	          # instruction-set optimized versions of code
 

meson.build

@@ -65,5 +65,5 @@ pkg.generate(name: meson.project_name(),
 			['-Wl,-Bdynamic'] + dpdk_extra_ldflags,
 	description: 'The Data Plane Development Kit (DPDK)',
 	subdirs: [get_option('include_subdir_arch'), '.'],
-	extra_cflags: ['-include', 'rte_config.h', '-march=@0@'.format(machine)]
+	extra_cflags: ['-include', 'rte_config.h', machine_arg]
 )