Re: [dpdk-dev] [PATCH v3] build: disable armv8 crypto extension

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

> 
> Per armv8 crypto extension support, make build always enable it by default as
> long as compiler supports the feature while meson build only enables it for
> 'default' machine of generic armv8 architecture.
> 
> It is known that not all the armv8 platforms have the crypto extension. For
> example, Mellanox BlueField has a variant which doesn't have it. If crypto
> enabled binary runs on such a platform, rte_eal_init() fails.
> 
> '+crypto' flag currently implies only '+aes' and '+sha2' and enabling it will
> generate the crypto instructions only when crypto intrinsics are used.
> For the devices supporting 8.2 crypto or newer, compiler could generate such
> instructions beyond intrinsics or asm code. For example, compiler can generate
> 3-way exclusive OR instructions if sha3 is supported. However, it has to be
> enabled by adding '+sha3' as of today.
> 
> In DPDK, armv8 cryptodev is the only one which requires the crypto support.
> As it even uses external library of Marvell which is compiled out of DPDK with
> crypto support and there's run-time check for required cpuflags, crypto
> support can be disabled in DPDK.
> 
> Cc: stable@dpdk.org
> 
> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> Acked-by: Jerin Jacob <jerinj@marvell.com>
> Tested-by: Dharmik Thakkar <dharmik.thakkar@arm.com>
> ---
> 
> v3:
> * announce removal of the flag in release note
> 
> v2:
> * disable crypto support instead of having a build config
> 
>  config/arm/meson.build                 | 2 +-
>  doc/guides/rel_notes/release_19_05.rst | 2 ++
>  mk/machine/armv8a/rte.vars.mk          | 2 +-
>  3 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/config/arm/meson.build b/config/arm/meson.build index
> 7fa6ed3105..abc8cf346c 100644
> --- a/config/arm/meson.build
> +++ b/config/arm/meson.build
> @@ -74,7 +74,7 @@ flags_octeontx2_extra = [
>  	['RTE_USE_C11_MEM_MODEL', true]]
> 
>  machine_args_generic = [
> -	['default', ['-march=armv8-a+crc+crypto']],
> +	['default', ['-march=armv8-a+crc']],
>  	['native', ['-march=native']],
>  	['0xd03', ['-mcpu=cortex-a53']],
>  	['0xd04', ['-mcpu=cortex-a35']],
> diff --git a/doc/guides/rel_notes/release_19_05.rst
> b/doc/guides/rel_notes/release_19_05.rst
> index 5044ac7df1..0d35f25094 100644
> --- a/doc/guides/rel_notes/release_19_05.rst
> +++ b/doc/guides/rel_notes/release_19_05.rst
> @@ -234,6 +234,8 @@ Removed Items
>     Also, make sure to start the actual text at the margin.
>     =========================================================
> 
> +* build: armv8 crypto extension is disabled.
> +
> 
>  API Changes
>  -----------
> diff --git a/mk/machine/armv8a/rte.vars.mk
> b/mk/machine/armv8a/rte.vars.mk index 8252efbb7b..5e3ffc3adf 100644
> --- a/mk/machine/armv8a/rte.vars.mk
> +++ b/mk/machine/armv8a/rte.vars.mk
> @@ -28,4 +28,4 @@
>  # CPU_LDFLAGS =
>  # CPU_ASFLAGS =
> 
> -MACHINE_CFLAGS += -march=armv8-a+crc+crypto
> +MACHINE_CFLAGS += -march=armv8-a+crc
> --
> 2.21.0

Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>