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From:   Niklas Cassel <Niklas.Cassel@wdc.com>
To:     Damien Le Moal <damien.lemoal@opensource.wdc.com>
CC:     Palmer Dabbelt <palmer@rivosinc.com>,
        "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        "aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
        "anup@brainfault.org" <anup@brainfault.org>,
        "heinrich.schuchardt@canonical.com" 
        <heinrich.schuchardt@canonical.com>,
        "atishp@atishpatra.org" <atishp@atishpatra.org>,
        "mchitale@ventanamicro.com" <mchitale@ventanamicro.com>,
        "alexandre.ghiti@canonical.com" <alexandre.ghiti@canonical.com>,
        "axboe@kernel.dk" <axboe@kernel.dk>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/3] RISC-V: K210 defconfigs: Drop redundant MEMBARRIER=n
Thread-Topic: [PATCH 2/3] RISC-V: K210 defconfigs: Drop redundant MEMBARRIER=n
Thread-Index: AQHYRJYETsVB7pr7MU2Y5E23WZPPL6zbwDkA
Date:   Sat, 2 Apr 2022 00:00:46 +0000
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On Thu, Mar 31, 2022 at 09:26:45AM +0900, Damien Le Moal wrote:
> On 3/31/22 08:47, Palmer Dabbelt wrote:
> > From: Palmer Dabbelt <palmer@rivosinc.com>
> >=20
> > As of 93917ad50972 ("RISC-V: Add support for restartable sequence") we
> > have support for restartable sequences, which default to enabled.  Thes=
e
> > select MEMBARRIER, so disabling it is now redundant.
> >=20
> > Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
> >=20
> > ---
> >=20
> > I'm not actually sure this is the right way to go: presumably the K210
> > defconfigs had MEMBARRIER=3Dn for a reason (maybe just size?), so we mi=
ght
> > actually want to move to RSEQ=3Dn instead?  As usual: I don't test on t=
he
> > K210, so I'm not exactly sure what the constraints are.
>=20
> Not sure either. It is like this now because I think this was the default
> at the time the config was created.
>=20
> Niklas,
>=20
> Can you test this please ?

Apologies for not being able to get back sooner.

I can see that this has already landed in Linus's tree:
a3dfc532b873 ("Merge tag 'riscv-for-linus-5.18-mw1' of git://git.kernel.org=
/pub/scm/linux/kernel/git/riscv/linux")

I smoke tested the above SHA1 on a k210 board, and on QEMU no-MMU
(since that defconfig was updated as well), and saw no issues.


Kind regards,
Niklas


>=20
> > ---
> >  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(-)
> >=20
> > diff --git a/arch/riscv/configs/nommu_k210_defconfig b/arch/riscv/confi=
gs/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=3Dy
> >  # 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=3Dy
> >  # CONFIG_VM_EVENT_COUNTERS is not set
> > diff --git a/arch/riscv/configs/nommu_k210_sdcard_defconfig b/arch/risc=
v/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=3Dy
> >  # 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=3Dy
> >  # CONFIG_VM_EVENT_COUNTERS is not set
> > diff --git a/arch/riscv/configs/nommu_virt_defconfig b/arch/riscv/confi=
gs/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=3Dy
> >  # 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
>=20
>=20
> --=20
> Damien Le Moal
> Western Digital Research=