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Wed, 17 Jun 2026 08:00:37 -0700 (PDT) Date: Wed, 17 Jun 2026 17:00:34 +0200 From: Petr Mladek To: Andrew Murray Cc: Jonathan Corbet , Shuah Khan , Russell King , Florian Fainelli , Broadcom internal kernel review list , Ray Jui , Scott Branden , Steven Rostedt , John Ogness , Sergey Senozhatsky , Andrew Morton , Sebastian Andrzej Siewior , Clark Williams , Randy Dunlap , Linus Torvalds , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH RFC 2/4] printk: deprecate boot_delay in favour of printk_delay Message-ID: References: <20260601-deprecate_boot_delay-v1-0-c34c187142a6@thegoodpenguin.co.uk> <20260601-deprecate_boot_delay-v1-2-c34c187142a6@thegoodpenguin.co.uk> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sun 2026-06-14 12:45:44, Andrew Murray wrote: > On Mon, 8 Jun 2026 at 15:07, Petr Mladek wrote: > > > > On Mon 2026-06-01 00:17:38, Andrew Murray wrote: > > > The boot_delay (BOOT_PRINTK_DELAY) kernel parameter and printk_delay sysctl > > > are two distinct mechanisms for providing similar functionality which add a > > > delay prior to each printed printk message. > > > > > > boot_delay provides a kernel parameter for delaying printk output from > > > kernel start through to boot (SYSTEM_RUNNING), whereas printk_delay is > > > configurable only via sysctl and thus is only used post boot. > > > > > > Let's deprecate the boot_delay feature in favour of printk_delay. In order > > > to preserve functionality, we'll also extend printk_delay such that it can > > > additionally configured via a kernel parameter. > > > > > --- a/kernel/printk/printk.c > > > +++ b/kernel/printk/printk.c > > > @@ -1339,11 +1327,34 @@ static void boot_delay_msec(int level) > > > } > > > } > > > #else > > > -static inline void boot_delay_msec(int level) > > > +static inline void __init printk_delay_calculate(void) > > > +{ > > > +} > > > + > > > +static inline void early_boot_delay_msec(void) > > > { > > > > It would be nice to print a warning that the early boot delay > > does not work, something like: > > > > pr_warn_once("Early boot delay does not work without CONFIG_GENERIC_CALIBRATE_DELAY enabled.\n"); > > > > > } > > > #endif > > > > > > +static int __init printk_delay_setup(char *str) > > > +{ > > > + get_option(&str, &printk_delay_msec); > > > + if (printk_delay_msec > 10 * 1000) > > > + printk_delay_msec = 0; > > > > Sashiko AI warns that this code accepts negative values. > > It might cause long delays, see > > https://sashiko.dev/#/patchset/20260601-deprecate_boot_delay-v1-0-c34c187142a6%40thegoodpenguin.co.uk > > > > The problem has already been there even before. But it would be nice > > to fix it. > > Thanks for pointing out Sashiko, I hadn't seen its review on my > patches. Are authors expected to get emails from it, as I didn't? Sashiko is able to send mails but it is opt-in. It might create too much noise because it has false positives, it keeps reporting minor or nice-to-fix problems which will "never" get fixed. Also it is not predictable so that you could not reliably check the patchset before sending. Anyway, I thought about enabling this for printk-related patches because Sashiko also gives a lot of useful feedback. And it is easier to discuss it as reply to a mail. But AFAIK, it can be done only per-mailing list. And printk does not have any dedicated mailing list. So, I "always" search for the feedback at https://sashiko.dev/ Best Regards, Petr