Re: [PATCH v4 0/4] arm64: cross-CPU NMI via SDEI

On Wed, Jun 17, 2026 at 08:20:01PM +0100, Kiryl Shutsemau wrote:
>   - A CPU stopped by the SDEI rung is parked, not powered off via PSCI
>     CPU_OFF. Reaching and dumping the wedged CPU -- the point of the
>     series -- works, and it matches the shared stop path's own park
>     fallback when CPU_OFF is unavailable. The consequence is that an SMP
>     crash-capture kernel cannot re-online such a CPU (it stays "already
>     on"); the capture kernel boots and runs on the remaining CPUs.
>     Powering the stopped CPU off so a capture kernel can reclaim it
>     requires completing the SDEI event and then CPU_OFF, which hit a
>     firmware-specific issue still under investigation; it is left as a
>     follow-up and does not affect the dump's contents.

Just to understand, your firmware cannot cope with a PSCI CPU_OFF from
the SDEI handler? This is one of the required calls to be supported.

-- 
Catalin