Re: [dpdk-dev] [RFC PATCH] build: allow passing extra config header to build

["David Harton (dharton)" <dharton@cisco.com>]

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Bruce Richardson
> Sent: Thursday, November 12, 2020 11:32 AM
> To: dev@dpdk.org
> Cc: Bruce Richardson <bruce.richardson@intel.com>
> Subject: [dpdk-dev] [RFC PATCH] build: allow passing extra config header
> to build
> 
> To allow per-build override of some settings, without having to change
> DPDK source-code files, i.e. rte_config.h, we can add an option to allow
> the user to pass in a file containing their own defines for the build.
> 

This is definitely better than what we have now.

Even going forward with this as a temp solution would be good while we work out longer-term strategy would be good.

What I believe is missing in the existing code base:
- knowing what all the knobs are
- ability to tune knobs in a build specific manner (providing per build config)

Regards,
Dave

> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
> This is just a quick RFC to show what might be possible and to help keep
> the discussion going on how to improve build config in DPDK!
> ---
>  config/meson.build  | 10 ++++++++++
>  config/rte_config.h |  4 ++++
>  meson_options.txt   |  2 ++
>  3 files changed, 16 insertions(+)
> 
> diff --git a/config/meson.build b/config/meson.build index
> 258b01d06..5c137e4f5 100644
> --- a/config/meson.build
> +++ b/config/meson.build
> @@ -14,6 +14,16 @@ foreach env:supported_exec_envs
>  	set_variable('is_' + env, exec_env == env)  endforeach
> 
> +if get_option('extra_config') != ''
> +	extra_config = files(get_option('extra_config'))
> +	configure_file(copy: true,
> +			input: extra_config,
> +			output: 'rte_build_config_extra.h',
> +			install_dir: join_paths(get_option('includedir'),
> +				get_option('include_subdir_arch')))
> +	dpdk_conf.set('RTE_BUILD_CONFIG_EXTRA', 1) endif
> +
>  # MS linker requires special treatment.
>  # TODO: use cc.get_linker_id() with Meson >= 0.54  is_ms_linker =
> is_windows and (cc.get_id() == 'clang') diff --git a/config/rte_config.h
> b/config/rte_config.h index 25219f04a..2f5ecf999 100644
> --- a/config/rte_config.h
> +++ b/config/rte_config.h
> @@ -148,4 +148,8 @@
>  #define RTE_LIBRTE_PMD_DLB2_SW_CREDIT_QUANTA 32  #define
> RTE_PMD_DLB2_DEFAULT_DEPTH_THRESH 256
> 
> +#ifdef RTE_BUILD_CONFIG_EXTRA
> +#include <rte_build_config_extra.h>
> +#endif
> +
>  #endif /* _RTE_CONFIG_H_ */
> diff --git a/meson_options.txt b/meson_options.txt index
> 9bf18ab6b..91319b0e4 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -2,6 +2,8 @@
> 
>  option('armv8_crypto_dir', type: 'string', value: '',
>  	description: 'path to the armv8_crypto library installation
> directory')
> +option('extra_config', type: 'string', value: '',
> +	description: 'path to a header file with extra build defines. Will
> be
> +installed as rte_build_config_extra.h')
>  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>',
> --
> 2.25.1