Re: [PATCH RFC] riscv: disable local interrupts and stop other CPUs before restart

Aurelien Jarno
2026-04-23T20:49:39Z

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

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Aurelien Jarno GPG: 4096R/1DDD8C9B
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