[dpdk-dev] [RFC PATCH] config: remap flags used for Arm platforms

[Ferruh Yigit]

On 8/14/2020 7:03 AM, Ruifeng Wang wrote:
> Flags are used to distinguish different platform architectures.
> These flags can be used to pick different code paths for different
> architectures at compile time.
> For Arm platforms, there are 3 flags in use: RTE_ARCH_ARM,
> RTE_ARCH_ARMv7 and RTE_ARCH_ARM64.
> RTE_ARCH_ARM64 is used to flag 64-bit aarch64 platforms,
> while RTE_ARCH_ARM & RTE_ARCH_ARMv7 are used to flag 32-bit platforms.
> RTE_ARCH_ARMv7 is for ARMv7 platforms as its name suggested.
> 
> The issue is that flag name RTE_ARCH_ARM is unclear and could cause
> confusion. No info about platform word length is included in the name.
> To make the flag names more clear, a naming scheme is proposed.
> 
>       RTE_ARCH_ARM
>           |
>           +----RTE_ARCH_ARM32
>           |        |
>           |        +----RTE_ARCH_ARMv7
>           |        |
>           |        +----RTE_ARCH_ARMv8_AARCH32
>           |
>           +----RTE_ARCH_ARM64
> 
> RTE_ARCH_ARM32 will be used for 32-bit Arm platforms.
> It includes RTE_ARCH_ARMv7 and RTE_ARCH_ARMv8_AARCH32.
> RTE_ARCH_ARMv7 is for ARMv7 platforms.
> RTE_ARCH_ARMv8_AARCH32 is for aarch32 state on aarch64 platforms.
> RTE_ARCH_ARM64 is for 64-bit Arm platforms.
> RTE_ARCH_ARM will be used for all Arm platforms, including RTE_ARCH_ARM32
> and RTE_ARCH_ARM64.
> 
> To fit into the new naming scheme, current usage of RTE_ARCH_ARM in
> project code is mapped to RTE_ARCH_ARM32.
> 
> Suggested-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
> Signed-off-by: Ruifeng Wang <ruifeng.wang at arm.com>
> Reviewed-by: Phil Yang <phil.yang at arm.com>
> ---

<...>

> @@ -6,7 +6,7 @@
>  CONFIG_RTE_MACHINE="armv7a"
>  
>  CONFIG_RTE_ARCH="arm"
> -CONFIG_RTE_ARCH_ARM=y
> +CONFIG_RTE_ARCH_ARM32=y
>  CONFIG_RTE_ARCH_ARMv7=y
>  CONFIG_RTE_ARCH_ARM_TUNE="cortex-a9"

According commit log message I thought 'RTE_ARCH_ARM' will be always set, isn't
it the case?

Is below wrong:
aarch64  -> ARM | ARM64 | ARCH_64
armv7a   -> ARM | ARM32 | ARMv7
aarch32  -> ARM | ARM32 | ARMv8_AARCH32

If so some of the 'defined(RTE_ARCH_ARM32) || defined(RTE_ARCH_ARM64)' checks
can be simplified as 'defined(RTE_ARCH_ARM)'


Also currently missing 'ARCH_64' flag implies the 32bit support, for all
architectures, what about having a common 'ARCH_32' flag and use for all arch,
instead of 'ARM32'? So something like below:
aarch64  -> ARM | ARM64 | ARCH_64
armv7a   -> ARM | ARMv7 | ARCH_32
aarch32  -> ARM | ARMv8_AARCH32 | ARCH_32




Just to record matching flags for other archs are:

x86_64  -> X86 | X86_64 | ARCH_64
i686    -> X86 | I686
x86_32  -> X86 | X86_32

ppc_64  -> PPC_64 | ARCH_64