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Tue, 20 Oct 2020 13:32:04 +0100 MIME-Version: 1.0 Date: Tue, 20 Oct 2020 13:32:03 +0100 From: Marc Zyngier To: Daniel Thompson Subject: Re: [PATCH v5 1/5] arm64: Add framework to turn IPI as NMI In-Reply-To: <20201020122535.paym32gksuhcqtwq@holly.lan> References: <1602673931-28782-1-git-send-email-sumit.garg@linaro.org> <1602673931-28782-2-git-send-email-sumit.garg@linaro.org> <20201020122535.paym32gksuhcqtwq@holly.lan> User-Agent: Roundcube Webmail/1.4.9 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: daniel.thompson@linaro.org, sumit.garg@linaro.org, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, tglx@linutronix.de, jason@lakedaemon.net, mark.rutland@arm.com, julien.thierry.kdev@gmail.com, dianders@chromium.org, jason.wessel@windriver.com, msys.mizuma@gmail.com, ito-yuichi@fujitsu.com, kgdb-bugreport@lists.sourceforge.net, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201020_083208_294905_96669B7E X-CRM114-Status: GOOD ( 15.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Sumit Garg , Jason Cooper , Catalin Marinas , ito-yuichi@fujitsu.com, Douglas Anderson , Linux Kernel Mailing List , julien.thierry.kdev@gmail.com, Jason Wessel , kgdb-bugreport@lists.sourceforge.net, Thomas Gleixner , Masayoshi Mizuma , Will Deacon , linux-arm-kernel Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-10-20 13:25, Daniel Thompson wrote: > On Tue, Oct 20, 2020 at 04:52:43PM +0530, Sumit Garg wrote: [...] >> So in general, IPI as a normal IRQ is still useful for debugging but >> it can't debug a core which is stuck in deadlock with interrupts >> disabled. >> >> And since we choose override default implementations for pseudo NMI >> support, we need to be backwards compatible for platforms which don't >> possess pseudo NMI support. > > Do the fallback implementations require a new IPI? The fallbacks > could rely on existing mechanisms such as the smp_call_function > family. Indeed. I'd be worried of using that mechanism for NMIs, but normal IPIs should stick to the normal cross-call stuff. The jury is still out on why this is a good idea, given that it doesn't work in the only interesting case (deadlocked CPUs). M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel