[dpdk-dev] [PATCH v2 01/17] eal: add max SIMD bitwidth

[Ananyev, Konstantin]

> This patch adds a max SIMD bitwidth EAL configuration. The API allows
> for an app to set this value. It can also be set using EAL argument
> --force-max-simd-bitwidth, which will lock the value and override any
> modifications made by the app.
> 
> Signed-off-by: Ciara Power <ciara.power at intel.com>
> 
> ---
> v2: Added to Doxygen comment for API.
> ---
>  lib/librte_eal/common/eal_common_options.c | 60 ++++++++++++++++++++++
>  lib/librte_eal/common/eal_internal_cfg.h   |  8 +++
>  lib/librte_eal/common/eal_options.h        |  2 +
>  lib/librte_eal/include/rte_eal.h           | 32 ++++++++++++
>  lib/librte_eal/rte_eal_version.map         |  4 ++
>  5 files changed, 106 insertions(+)
> 
> diff --git a/lib/librte_eal/common/eal_common_options.c b/lib/librte_eal/common/eal_common_options.c
> index a5426e1234..90f4e8f5c3 100644
> --- a/lib/librte_eal/common/eal_common_options.c
> +++ b/lib/librte_eal/common/eal_common_options.c
> @@ -102,6 +102,7 @@ eal_long_options[] = {
>  	{OPT_MATCH_ALLOCATIONS, 0, NULL, OPT_MATCH_ALLOCATIONS_NUM},
>  	{OPT_TELEMETRY,         0, NULL, OPT_TELEMETRY_NUM        },
>  	{OPT_NO_TELEMETRY,      0, NULL, OPT_NO_TELEMETRY_NUM     },
> +	{OPT_FORCE_MAX_SIMD_BITWIDTH, 1, NULL, OPT_FORCE_MAX_SIMD_BITWIDTH_NUM},
>  	{0,                     0, NULL, 0                        }
>  };
> 
> @@ -1309,6 +1310,32 @@ eal_parse_iova_mode(const char *name)
>  	return 0;
>  }
> 
> +static int
> +eal_parse_simd_bitwidth(const char *arg, bool locked)
> +{
> +	char *end;
> +	uint16_t bitwidth;
> +	int ret;
> +	struct internal_config *internal_conf =
> +		eal_get_internal_configuration();
> +
> +	if (arg == NULL || arg[0] == '\0')
> +		return -1;
> +
> +	errno = 0;
> +	bitwidth = strtoul(arg, &end, 0);

As I can see with that assignment you'll loose high bits set (if any).
So, --force-max-simd-bitwidth=0xf0080
wouldn't report any error, while it probably should.
Probably something like that, as abetter way:
unsigned long t;
...
t = strtoul(arg, &end, 0);
if (t > UINT16_MAX || errno != 0 || end == NULL || *end != '\0')
	return -1;
ret = rte_set_max_simd_bitwidth(t);

> +
> +	/* check for errors */
> +	if ((errno != 0) || end == NULL || (*end != '\0'))
> +		return -1;
> +
> +	ret = rte_set_max_simd_bitwidth(bitwidth);
> +	if (ret < 0)
> +		return -1;
> +	internal_conf->max_simd_bitwidth.locked = locked;
> +	return 0;
> +}
> +