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From: Aurelien Jarno <aurelien@aurel32.net>
To: Samuel Holland <samuel.holland@sifive.com>
Cc: Troy Mitchell <troy.mitchell@linux.dev>,
	Vivian Wang <wangruikang@iscas.ac.cn>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] riscv: disable local interrupts and stop other CPUs before restart
Date: Thu, 23 Apr 2026 22:49:20 +0200	[thread overview]
Message-ID: <aeqF0EiP4b2Ycj2G@aurel32.net> (raw)
In-Reply-To: <c1f466f8-4e76-43a2-a7a2-126415fd1f56@sifive.com>

Hi,

On 2026-03-16 08:19, Samuel Holland wrote:
> Hi Troy,
> 
> On 2026-03-16 2:23 AM, Troy Mitchell wrote:
> >> I think the reason we ended up with the "unsafe" implementations of the
> >> reboot/shutdown functions is that on the backend it is usually SBI SRST
> >> calls, which can protect itself from other CPUs and interrupts. Since on
> >> K1 we're going to be poking I2C directly, we run into the problem
> >> described above. So all of these should disable interrupts and stop
> >> other CPUs before calling the handlers, and can't assume the handlers
> >> are all SBI SRST.
> > Yes, we cannot assume that all platforms rely on this.
> 
> Why isn't K1 using the SBI SRST extension? Resetting the platform from S-mode
> directly causes problems if you ever want to run another supervisor domain (for
> example a TEE or EFI runtime services), which may need to clean up before a
> system reset.
> 
> As you mention, other platforms use the standard SBI SRST interface, event if
> they need to poke a PMIC to perform a system reset. Is there something
> preventing K1 from following this path?

I went this path and submitted a patchset to OpenSBI mailing list doing 
that:
https://lore.kernel.org/opensbi/20260419150857.2705843-1-aurelien@aurel32.net/T/#t

Regards
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                     http://aurel32.net

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WARNING: multiple messages have this Message-ID (diff)
From: Aurelien Jarno <aurelien@aurel32.net>
To: Samuel Holland <samuel.holland@sifive.com>
Cc: Troy Mitchell <troy.mitchell@linux.dev>,
	Vivian Wang <wangruikang@iscas.ac.cn>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] riscv: disable local interrupts and stop other CPUs before restart
Date: Thu, 23 Apr 2026 22:49:20 +0200	[thread overview]
Message-ID: <aeqF0EiP4b2Ycj2G@aurel32.net> (raw)
In-Reply-To: <c1f466f8-4e76-43a2-a7a2-126415fd1f56@sifive.com>

Hi,

On 2026-03-16 08:19, Samuel Holland wrote:
> Hi Troy,
> 
> On 2026-03-16 2:23 AM, Troy Mitchell wrote:
> >> I think the reason we ended up with the "unsafe" implementations of the
> >> reboot/shutdown functions is that on the backend it is usually SBI SRST
> >> calls, which can protect itself from other CPUs and interrupts. Since on
> >> K1 we're going to be poking I2C directly, we run into the problem
> >> described above. So all of these should disable interrupts and stop
> >> other CPUs before calling the handlers, and can't assume the handlers
> >> are all SBI SRST.
> > Yes, we cannot assume that all platforms rely on this.
> 
> Why isn't K1 using the SBI SRST extension? Resetting the platform from S-mode
> directly causes problems if you ever want to run another supervisor domain (for
> example a TEE or EFI runtime services), which may need to clean up before a
> system reset.
> 
> As you mention, other platforms use the standard SBI SRST interface, event if
> they need to poke a PMIC to perform a system reset. Is there something
> preventing K1 from following this path?

I went this path and submitted a patchset to OpenSBI mailing list doing 
that:
https://lore.kernel.org/opensbi/20260419150857.2705843-1-aurelien@aurel32.net/T/#t

Regards
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                     http://aurel32.net

  parent reply	other threads:[~2026-04-23 20:49 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-11  2:51 [PATCH RFC] riscv: disable local interrupts and stop other CPUs before restart Troy Mitchell
2026-03-11  2:51 ` Troy Mitchell
2026-03-11  6:47 ` Aurelien Jarno
2026-03-11  6:47   ` Aurelien Jarno
2026-03-11  9:49   ` Troy Mitchell
2026-03-11  9:49     ` Troy Mitchell
2026-03-11  9:54     ` Troy Mitchell
2026-03-11  9:54       ` Troy Mitchell
2026-03-12  3:05 ` Vivian Wang
2026-03-12  3:05   ` Vivian Wang
2026-03-16  7:23   ` Troy Mitchell
2026-03-16  7:23     ` Troy Mitchell
2026-03-16 13:19     ` Samuel Holland
2026-03-16 13:19       ` Samuel Holland
2026-03-17  2:45       ` Troy Mitchell
2026-03-17  2:45         ` Troy Mitchell
2026-03-17  4:07         ` Samuel Holland
2026-03-17  4:07           ` Samuel Holland
2026-03-17  7:42           ` Troy Mitchell
2026-03-17  7:42             ` Troy Mitchell
2026-04-23 20:49       ` Aurelien Jarno [this message]
2026-04-23 20:49         ` Aurelien Jarno
2026-04-25 17:42         ` Anand Moon
2026-04-25 17:42           ` Anand Moon
2026-04-26 12:20           ` Aurelien Jarno
2026-04-26 12:20             ` Aurelien Jarno
2026-04-27  3:47             ` Anand Moon
2026-04-27  3:47               ` Anand Moon
2026-05-04 13:27             ` Anand Moon
2026-05-04 13:27               ` Anand Moon

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