Re: [dpdk-dev] [RFC PATCH v2] build: add platform meson option

["Juraj Linkeš" <juraj.linkes@pantheon.tech>]

Apologies, I meant to add David as well.

> -----Original Message-----
> From: Juraj Linkeš <juraj.linkes@pantheon.tech>
> Sent: Monday, January 4, 2021 12:52 PM
> To: thomas@monjalon.net; bruce.richardson@intel.com;
> Honnappa.Nagarahalli@arm.com
> Cc: dev@dpdk.org; Juraj Linkeš <juraj.linkes@pantheon.tech>
> Subject: [RFC PATCH v2] build: add platform meson option
> 
> The current meson option 'machine' should only specify the ISA, which is not
> sufficient for Arm, where setting ISA implies other setting as well.
> Add a new meson option, 'platform', which differentiates the type of the build
> (native/generic) and sets machine accordingly, unless the user chooses to
> override it.
> The 'machine' option also doesn't describe very well what it sets, so introduce a
> new option 'cpu_instruction_set', but keep 'machine' for backward
> compatibility.
> These two new variables, taken together, achieve what 'machine' was setting
> per architecture - setting the ISA in x86 build and setting native/default 'build
> type' in aarch64 build - is now properly being set for all architectures in a
> uniform manner.
> 
> Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
> ---
>  config/arm/meson.build        |  4 +--
>  config/meson.build            | 47 +++++++++++++++++++++++++----------
>  devtools/test-meson-builds.sh |  9 ++++---
>  meson_options.txt             |  8 ++++--
>  4 files changed, 47 insertions(+), 21 deletions(-)
> 
> diff --git a/config/arm/meson.build b/config/arm/meson.build index
> 42b4e43c7..6b09a74a7 100644
> --- a/config/arm/meson.build
> +++ b/config/arm/meson.build
> @@ -3,10 +3,10 @@
>  # Copyright(c) 2017 Cavium, Inc
> 
>  # for checking defines we need to use the correct compiler flags -march_opt = '-
> march=@0@'.format(machine)
> +march_opt = '-march=@0@'.format(cpu_instruction_set)
> 
>  arm_force_native_march = false
> -arm_force_default_march = (machine == 'default')
> +arm_force_default_march = (platform == 'generic')
> 
>  flags_common_default = [
>  	# Accelarate rte_memcpy. Be sure to run unit test
> (memcpy_perf_autotest) diff --git a/config/meson.build b/config/meson.build
> index a3154e29c..647116513 100644
> --- a/config/meson.build
> +++ b/config/meson.build
> @@ -63,42 +63,63 @@ if not is_windows
>  			pmd_subdir_opt)
>  endif
> 
> -# set the machine type and cflags for it
> +platform = get_option('platform')
> +
> +# set the cpu_instruction_set type and cflags for it
>  if meson.is_cross_build()
> -	machine = host_machine.cpu()
> +	cpu_instruction_set = host_machine.cpu()
>  else
> -	machine = get_option('machine')
> +	cpu_instruction_set = get_option('cpu_instruction_set')
> +	if get_option('machine') != 'auto'
> +		warning('The "machine" option is deprecated. ' +
> +		        'Please use "cpu_instruction_set" instead.')
> +		if cpu_instruction_set != 'auto'
> +			error('Setting both "machine" and ' +
> +			      '"cpu_instruction_set" is unsupported.')
> +		endif
> +		cpu_instruction_set = get_option('machine')
> +	endif
> +endif
> +
> +if platform == 'native'
> +	if cpu_instruction_set == 'auto'
> +		cpu_instruction_set = 'native'
> +	endif
> +elif platform == 'generic'
> +	if cpu_instruction_set == 'auto'
> +		cpu_instruction_set = 'default'
> +	endif
>  endif
> 
> -# machine type 'default' is special, it defaults to the per arch agreed common
> +if cpu_instruction_set == 'default'
> +# cpu_instruction_set type 'default' is special, it defaults to the per
> +arch agreed common
>  # minimal baseline needed for DPDK.
>  # 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 host_machine.cpu_family().startswith('x86')
>  		# matches the old pre-meson build systems default
> -		machine = 'corei7'
> +		cpu_instruction_set = 'corei7'
>  	elif host_machine.cpu_family().startswith('arm')
> -		machine = 'armv7-a'
> +		cpu_instruction_set = 'armv7-a'
>  	elif host_machine.cpu_family().startswith('aarch')
>  		# arm64 manages defaults in config/arm/meson.build
> -		machine = 'default'
> +		cpu_instruction_set = 'default'
>  	elif host_machine.cpu_family().startswith('ppc')
> -		machine = 'power8'
> +		cpu_instruction_set = 'power8'
>  	endif
>  endif
> 
> -dpdk_conf.set('RTE_MACHINE', machine)
> +dpdk_conf.set('RTE_MACHINE', cpu_instruction_set)
>  machine_args = []
> 
>  # ppc64 does not support -march= at all, use -mcpu and -mtune for that  if
> host_machine.cpu_family().startswith('ppc')
> -	machine_args += '-mcpu=' + machine
> -	machine_args += '-mtune=' + machine
> +	machine_args += '-mcpu=' + cpu_instruction_set
> +	machine_args += '-mtune=' + cpu_instruction_set
>  else
> -	machine_args += '-march=' + machine
> +	machine_args += '-march=' + cpu_instruction_set
>  endif
> 
>  toolchain = cc.get_id()
> diff --git a/devtools/test-meson-builds.sh b/devtools/test-meson-builds.sh index
> 7280b7a93..33845d998 100755
> --- a/devtools/test-meson-builds.sh
> +++ b/devtools/test-meson-builds.sh
> @@ -211,11 +211,12 @@ done
>  # test compilation with minimal x86 instruction set  # Set the install path for
> libraries to "lib" explicitly to prevent problems  # with pkg-config prefixes if
> installed in "lib/x86_64-linux-gnu" later.
> -default_machine='nehalem'
> -if ! check_cc_flags "-march=$default_machine" ; then
> -	default_machine='corei7'
> +default_isa='nehalem'
> +if ! check_cc_flags "-march=$default_isa" ; then
> +	default_isa='corei7'
>  fi
> -build build-x86-default cc -Dlibdir=lib -Dmachine=$default_machine
> $use_shared
> +build build-x86-default cc -Dlibdir=lib -Dcpu_instruction_set=$default_isa \
> +      $use_shared
> 
>  # 32-bit with default compiler
>  if check_cc_flags '-m32' ; then
> diff --git a/meson_options.txt b/meson_options.txt index
> e384e6dbb..9db03a87d 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -1,5 +1,7 @@
>  # Please keep these options sorted alphabetically.
> 
> +option('cpu_instruction_set', type: 'string', value: 'auto',
> +	description: 'Set the target machine ISA (instruction set
> +architecture)/')
>  option('disable_drivers', type: 'string', value: '',
>  	description: 'Comma-separated list of drivers to explicitly disable.')
> option('drivers_install_subdir', type: 'string', value: 'dpdk/pmds-<VERSION>',
> @@ -20,14 +22,16 @@ option('kernel_dir', type: 'string', value: '',
>  	description: 'Path to the kernel for building kernel modules. Headers
> must be in $kernel_dir/build. Modules will be installed in
> $DEST_DIR/$kernel_dir/extra/dpdk.')
>  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')
> +option('machine', type: 'string', value: 'auto',
> +	description: 'set the target machine type/ISA')
>  option('max_ethports', type: 'integer', value: 32,
>  	description: 'maximum number of Ethernet devices')
> option('max_lcores', type: 'integer', value: 128,
>  	description: 'maximum number of cores/threads supported by EAL')
> option('max_numa_nodes', type: 'integer', value: 4,
>  	description: 'maximum number of NUMA nodes supported by EAL')
> +option('platform', type: 'string', value: 'generic',
> +	description: 'Platform to build for, either "native" or "generic".')
>  option('enable_trace_fp', type: 'boolean', value: false,
>  	description: 'enable fast path trace points.')  option('tests', type:
> 'boolean', value: true,
> --
> 2.20.1