On Thu, Jul 09, 2026 at 05:16:37PM +0100, Kiryl Shutsemau wrote: > On Mon, Jun 29, 2026 at 04:07:14PM +0100, Kiryl Shutsemau wrote: > > From: "Kiryl Shutsemau (Meta)" <[email protected]> > > > > A class of debug/observability features needs to interrupt a CPU that has > > its interrupts locally masked: the all-CPU backtrace behind sysrq-l / > > RCU-stall / hung-task / hard-lockup dumps, and crash_smp_send_stop() > > capturing a stuck CPU's state into the vmcore. On arm64 these need a > > mechanism that reaches a CPU spinning with DAIF masked, which a normal IPI > > cannot. > > Gentle ping. Any feedback? > > I'm looking forward to finding an upstreamable solution to the problem.
This is all pretty small, self-contained and it's useful to you, so I'm inclined to merge it. However, the one vague concern I have is about the direction of SDEI in the future. AFAIK, the TF-A implementation is known to have issues, it's not supported at all by R-FA and I worry that the spec is going to fall behind the architecture, particularly as FEAT_NMI becomes available. So it would be good to understand what we're signing up to maintain here. Kiryl, do you see an (eventual) migration over to FEAT_NMI, giving us a path to deprecating SDEI altogether, or do you think the two will live alongside each other for the forseeable future? Cheers, Will
