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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/2/20 6:02 AM, Ivan Mikhaylov wrote: > Hello everyone. Currently, the watchdog interface only has "stop watchdog on > restart" but lacks a "start watchdog on restart" one. Is there a way to achieve > such functionality? > > I'd like to know why "stop watchdog on restart" wasn't implemented via ioctl > interface? It would be more convenient from user perspective and you can > control that behavior whenever you want from application layer. > Because it is and always was a driver level decision. The function was added to replace lots of driver level code implementing this functionality. Overriding it from userspace doesn't make sense because the driver is supposed to have a reason for disabling it on reboot (for example due to clock issues or power issues or becasue it has a short hardware timeout). > I have some thoughts on this problem that solve the aforementioned > issue with "start watchdog on restart" but I don't think that my solution is > correct. > That functionality doesn't make much sense. It can be accomplished by not stopping the watchdog on reboot in the first place. And if the watchdog wasn't running before, it can be started from userspace just before the reboot. Guenter