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Wysocki" , Lecopzer Chen , Wei Li , linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 7/7] arm64: kgdb: Roundup cpus using the debug IPI In-Reply-To: References: <20230601213440.2488667-1-dianders@chromium.org> <20230601143109.v9.7.I2ef26d1b3bfbed2d10a281942b0da7d9854de05e@changeid> User-Agent: Roundcube Webmail/1.4.13 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 217.182.43.188 X-SA-Exim-Rcpt-To: mark.rutland@arm.com, dianders@chromium.org, catalin.marinas@arm.com, will@kernel.org, sumit.garg@linaro.org, daniel.thompson@linaro.org, linux-perf-users@vger.kernel.org, ito-yuichi@fujitsu.com, wens@csie.org, ardb@kernel.org, swboyd@chromium.org, peterz@infradead.org, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, kgdb-bugreport@lists.sourceforge.net, msys.mizuma@gmail.com, rafael.j.wysocki@intel.com, lecopzer.chen@mediatek.com, liwei391@huawei.com, 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-20230807_114716_027899_FE25AE0F X-CRM114-Status: GOOD ( 17.04 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 2023-08-07 11:28, Mark Rutland wrote: > On Thu, Jun 01, 2023 at 02:31:51PM -0700, Douglas Anderson wrote: >> From: Sumit Garg >> >> Let's use the debug IPI for rounding up CPUs in kgdb. When the debug >> IPI is backed by an NMI (or pseudo NMI) then this will let us debug >> even hard locked CPUs. When the debug IPI isn't backed by an NMI then >> this won't really have any huge benefit but it will still work. >> >> Signed-off-by: Sumit Garg >> Signed-off-by: Douglas Anderson >> --- >> >> Changes in v9: >> - Remove fallback for when debug IPI isn't available. >> - Renamed "NMI IPI" to "debug IPI" since it might not be backed by >> NMI. >> >> arch/arm64/kernel/ipi_debug.c | 5 +++++ >> arch/arm64/kernel/kgdb.c | 14 ++++++++++++++ >> 2 files changed, 19 insertions(+) > > This looks fine to me, but I'd feel a bit happier if we had separate > SGIs for > the backtrace and the KGDB callback as they're logically unrelated. Well, we're a bit stuck here. We have exactly *one* spare SGI with GICv3, as we lose 8 of them to the secure side. One possibility would be to mux some of the lesser used IPIs onto two SGIs (one with standard priority, and one with NMI priority). 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