linux-kernel - Re: [PATCH 2/3] RISC-V: K210 defconfigs: Drop redundant MEMBARRIER=n

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Message-ID: <d8a35bea-f4a0-b54d-9d2a-d1cc9b3d3e53@opensource.wdc.com>
Date:   Thu, 31 Mar 2022 09:26:45 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Palmer Dabbelt <palmer@...osinc.com>,
        linux-riscv@...ts.infradead.org,
        Niklas Cassel <Niklas.Cassel@....com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>, aou@...s.berkeley.edu,
        anup@...infault.org, heinrich.schuchardt@...onical.com,
        atishp@...shpatra.org, mchitale@...tanamicro.com,
        alexandre.ghiti@...onical.com, axboe@...nel.dk,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] RISC-V: K210 defconfigs: Drop redundant MEMBARRIER=n

On 3/31/22 08:47, Palmer Dabbelt wrote:
> From: Palmer Dabbelt <palmer@...osinc.com>
> 
> As of 93917ad50972 ("RISC-V: Add support for restartable sequence") we
> have support for restartable sequences, which default to enabled.  These
> select MEMBARRIER, so disabling it is now redundant.
> 
> Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
> 
> ---
> 
> I'm not actually sure this is the right way to go: presumably the K210
> defconfigs had MEMBARRIER=n for a reason (maybe just size?), so we might
> actually want to move to RSEQ=n instead?  As usual: I don't test on the
> K210, so I'm not exactly sure what the constraints are.

Not sure either. It is like this now because I think this was the default
at the time the config was created.

Niklas,

Can you test this please ?

> ---
>  arch/riscv/configs/nommu_k210_defconfig        | 1 -
>  arch/riscv/configs/nommu_k210_sdcard_defconfig | 1 -
>  arch/riscv/configs/nommu_virt_defconfig        | 1 -
>  3 files changed, 3 deletions(-)
> 
> diff --git a/arch/riscv/configs/nommu_k210_defconfig b/arch/riscv/configs/nommu_k210_defconfig
> index 3f42ed87dde8..2438fa39f8ae 100644
> --- a/arch/riscv/configs/nommu_k210_defconfig
> +++ b/arch/riscv/configs/nommu_k210_defconfig
> @@ -21,7 +21,6 @@ CONFIG_CC_OPTIMIZE_FOR_SIZE=y
>  # CONFIG_AIO is not set
>  # CONFIG_IO_URING is not set
>  # CONFIG_ADVISE_SYSCALLS is not set
> -# CONFIG_MEMBARRIER is not set
>  # CONFIG_KALLSYMS is not set
>  CONFIG_EMBEDDED=y
>  # CONFIG_VM_EVENT_COUNTERS is not set
> diff --git a/arch/riscv/configs/nommu_k210_sdcard_defconfig b/arch/riscv/configs/nommu_k210_sdcard_defconfig
> index af64b95e88cc..9a133e63ae5b 100644
> --- a/arch/riscv/configs/nommu_k210_sdcard_defconfig
> +++ b/arch/riscv/configs/nommu_k210_sdcard_defconfig
> @@ -13,7 +13,6 @@ CONFIG_CC_OPTIMIZE_FOR_SIZE=y
>  # CONFIG_AIO is not set
>  # CONFIG_IO_URING is not set
>  # CONFIG_ADVISE_SYSCALLS is not set
> -# CONFIG_MEMBARRIER is not set
>  # CONFIG_KALLSYMS is not set
>  CONFIG_EMBEDDED=y
>  # CONFIG_VM_EVENT_COUNTERS is not set
> diff --git a/arch/riscv/configs/nommu_virt_defconfig b/arch/riscv/configs/nommu_virt_defconfig
> index e1c9864b6237..5269fbb6b4fc 100644
> --- a/arch/riscv/configs/nommu_virt_defconfig
> +++ b/arch/riscv/configs/nommu_virt_defconfig
> @@ -19,7 +19,6 @@ CONFIG_EXPERT=y
>  # CONFIG_AIO is not set
>  # CONFIG_IO_URING is not set
>  # CONFIG_ADVISE_SYSCALLS is not set
> -# CONFIG_MEMBARRIER is not set
>  # CONFIG_KALLSYMS is not set
>  # CONFIG_VM_EVENT_COUNTERS is not set
>  # CONFIG_COMPAT_BRK is not set


-- 
Damien Le Moal
Western Digital Research