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[82.132.221.219]) by smtp.gmail.com with ESMTPSA id m1sm8647311wmc.28.2020.08.13.03.17.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Aug 2020 03:17:06 -0700 (PDT) Date: Thu, 13 Aug 2020 11:17:03 +0100 From: Daniel Thompson To: Sumit Garg Cc: Doug Anderson , Greg Kroah-Hartman , linux-serial@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net, Jiri Slaby , Russell King - ARM Linux admin , Jason Wessel , Linux Kernel Mailing List , linux-arm-kernel Subject: Re: [RFC 0/5] Introduce NMI aware serial drivers Message-ID: <20200813101703.566thqmnc2d7cb3n@holly.lan> References: <1595333413-30052-1-git-send-email-sumit.garg@linaro.org> <20200811135801.GA416071@kroah.com> <20200811145816.GA424033@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Thu, Aug 13, 2020 at 02:55:12PM +0530, Sumit Garg wrote: > On Thu, 13 Aug 2020 at 05:38, Doug Anderson wrote: > > On Wed, Aug 12, 2020 at 8:27 AM Doug Anderson wrote: > > > One > > > last worry is that I assume that most people testing (and even > > > automated testing labs) will either always enable NMI or won't enable > > > NMI. That means that everyone will be only testing one codepath or > > > the other and (given the complexity) the non-tested codepath will > > > break. > > > > > The current patch-set only makes this NMI to work when debugger (kgdb) > is enabled which I think is mostly suitable for development > environments. So most people testing will involve existing IRQ mode > only. > > However, it's very much possible to make NMI mode as default for a > particular serial driver if the underlying irqchip supports it but it > depends if we really see any production level usage of NMI debug > feature. The effect of this patch is not to make kgdb work from NMI it is to make (some) SysRqs work from NMI. I think that only allowing it to deploy for kgdb users is a mistake. Having it deploy automatically for kgdb users might be OK but it seems sensible to make this feature available for other users too. Daniel.