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([2001:8a0:fae3:2600:bf49:e032:9c8d:efc8]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490ea83d8dasm90477965e9.11.2026.06.12.07.20.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Jun 2026 07:20:41 -0700 (PDT) Message-ID: <222c9287-4e69-457d-ad91-fd1586f171cf@palves.net> Date: Fri, 12 Jun 2026 15:20:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 00/11] Enable non-stop mode by default for remote targets To: Mohamed Bouhaouel , gdb-patches@sourceware.org Cc: stephan.rohr@intel.com, markus.t.metzger@intel.com References: <20260518183316.127043-1-mohamed.bouhaouel@intel.com> From: Pedro Alves Content-Language: en-US In-Reply-To: <20260518183316.127043-1-mohamed.bouhaouel@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces~public-inbox=simark.ca@sourceware.org On 2026-05-18 19:32, Mohamed Bouhaouel wrote: > From: "Bouhaouel, Mohamed" > > This series makes remote targets operate in non-stop mode if the target > announces QNonStop support and 'maint set target-non-stop’ is set to > ‘auto', aligning the behavior with the Linux native target. This wasn't done before for a reason. It's that 'maint set target-non-stop on’ does not support all the features the all-stop variant of the remote protocol. Specifically, off the top of my head: - there is no alternative to the O packet. Those can be sent while the target is running as if they were a stop reply, but that doesn't work in non-stop mode. See remote_target::wait_as: case 'O': /* Console output. */ - remote file I/O support does not work. Similar to the O packet. See remote_target::wait_as: case 'F': /* File-I/O request. */ - packet efficiency. With non-stop, GDB suspends and resumes each thread individually. - on the resumption side, that is mitigated by GDB coalescing vCont packets. when you e.g. "continue", gdb core does one target_resume call per thread, but the remote target backend does not resume the thread immediately. Instead, it defers the resume until infrun calls target_commit_resumed(). - on the stopping side, however, there is no support for aggregation. The server reports each thread stop with its own separate stop reply notification. So it's plausible that there may some stubs out there that do support non-stop mode, but they also support e.g., file I/O. Enabling non-stop by default for those might not be the correct choice. Or maybe the performance degrades visibly. Maybe there are some mitigating factors, like, maybe it won't matter that much if we have displaced stepping. My point is, this needs to be a considered change, not just "to align with linux". Pedro Alves