From: Peter Geis <pgwipeout@gmail.com> To: John Ogness <john.ogness@linutronix.de> Cc: Petr Mladek <pmladek@suse.com>, Sergey Senozhatsky <senozhatsky@chromium.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org> Subject: Re: [BUG] Threaded printk breaks early debugging Date: Fri, 10 Jun 2022 11:34:47 -0400 [thread overview] Message-ID: <CAMdYzYr-Wo713Y4qjboTpoK6GcrYfKCfRJAEizwXw6-=dymVzg@mail.gmail.com> (raw) In-Reply-To: <87y1y48spg.fsf@jogness.linutronix.de> On Fri, Jun 10, 2022 at 11:05 AM John Ogness <john.ogness@linutronix.de> wrote: > > Hi Peter, > > On 2022-06-10, Peter Geis <pgwipeout@gmail.com> wrote: > > However I've run into an issue debugging early boot issues. Anything > > that causes the kernel threading system to die (for example here, a > > NPE) causes the boot console to halt before it outputs the error. > > A null pointer exception should trigger a panic, which will cause printk > to enter direct mode for the oops. It should be just as effective as > before introducing the printing kthreads. This might be a side effect of the fact that this is on a low powered arm64 board. I noticed with threading enabled during large bursts the console drops an excessive amount of messages. It's especially apparent during the handover from earlycon to the normal console. > > Can you please provide a test case or patch that will trigger the > problem you refer to? Unfortunately no, unless you have a Rockchip rk356x device with both DSI and HDMI. We're working on adding DSI support to the new video output driver, and when both are enabled it tosses a NPE. > > > Would it be possible to have both a kconfig option and a runtime > > option to toggle printk_fallback_preferred_direct()? Currently I've > > had to force it at all times while debugging. > > It would be trivial to provide a boot parameter for this behavior, but I > think we first need to see a real problem and also see if we can fix > that problem. > > John Ogness
WARNING: multiple messages have this Message-ID (diff)
From: Peter Geis <pgwipeout@gmail.com> To: John Ogness <john.ogness@linutronix.de> Cc: Petr Mladek <pmladek@suse.com>, Sergey Senozhatsky <senozhatsky@chromium.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org> Subject: Re: [BUG] Threaded printk breaks early debugging Date: Fri, 10 Jun 2022 11:34:47 -0400 [thread overview] Message-ID: <CAMdYzYr-Wo713Y4qjboTpoK6GcrYfKCfRJAEizwXw6-=dymVzg@mail.gmail.com> (raw) In-Reply-To: <87y1y48spg.fsf@jogness.linutronix.de> On Fri, Jun 10, 2022 at 11:05 AM John Ogness <john.ogness@linutronix.de> wrote: > > Hi Peter, > > On 2022-06-10, Peter Geis <pgwipeout@gmail.com> wrote: > > However I've run into an issue debugging early boot issues. Anything > > that causes the kernel threading system to die (for example here, a > > NPE) causes the boot console to halt before it outputs the error. > > A null pointer exception should trigger a panic, which will cause printk > to enter direct mode for the oops. It should be just as effective as > before introducing the printing kthreads. This might be a side effect of the fact that this is on a low powered arm64 board. I noticed with threading enabled during large bursts the console drops an excessive amount of messages. It's especially apparent during the handover from earlycon to the normal console. > > Can you please provide a test case or patch that will trigger the > problem you refer to? Unfortunately no, unless you have a Rockchip rk356x device with both DSI and HDMI. We're working on adding DSI support to the new video output driver, and when both are enabled it tosses a NPE. > > > Would it be possible to have both a kconfig option and a runtime > > option to toggle printk_fallback_preferred_direct()? Currently I've > > had to force it at all times while debugging. > > It would be trivial to provide a boot parameter for this behavior, but I > think we first need to see a real problem and also see if we can fix > that problem. > > John Ogness _______________________________________________ Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip
next prev parent reply other threads:[~2022-06-10 15:35 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-06-10 12:48 [BUG] Threaded printk breaks early debugging Peter Geis 2022-06-10 12:48 ` Peter Geis 2022-06-10 15:05 ` John Ogness 2022-06-10 15:05 ` John Ogness 2022-06-10 15:34 ` Peter Geis [this message] 2022-06-10 15:34 ` Peter Geis 2022-06-12 2:57 ` Sergey Senozhatsky 2022-06-12 2:57 ` Sergey Senozhatsky 2022-06-12 13:30 ` Peter Geis 2022-06-12 13:30 ` Peter Geis 2022-06-12 23:08 ` John Ogness 2022-06-12 23:08 ` John Ogness 2022-06-12 23:30 ` Peter Geis 2022-06-12 23:30 ` Peter Geis 2022-06-13 2:23 ` John Ogness 2022-06-13 2:23 ` John Ogness 2022-06-13 15:11 ` Petr Mladek 2022-06-13 15:11 ` Petr Mladek 2022-06-13 22:20 ` Peter Geis 2022-06-13 22:20 ` Peter Geis 2022-06-14 8:38 ` Petr Mladek 2022-06-14 8:38 ` Petr Mladek 2022-06-13 11:24 ` Petr Mladek 2022-06-13 11:24 ` Petr Mladek 2022-06-12 3:13 ` Sergey Senozhatsky 2022-06-12 3:13 ` Sergey Senozhatsky 2022-06-12 23:02 ` John Ogness 2022-06-12 23:02 ` John Ogness 2022-06-13 3:49 ` Sergey Senozhatsky 2022-06-13 3:49 ` Sergey Senozhatsky 2022-06-13 8:30 ` John Ogness 2022-06-13 8:30 ` John Ogness 2022-06-13 9:05 ` Sergey Senozhatsky 2022-06-13 9:05 ` Sergey Senozhatsky 2022-06-13 10:14 ` Petr Mladek 2022-06-13 10:14 ` Petr Mladek 2022-06-13 16:11 ` David Laight 2022-06-13 16:11 ` David Laight 2022-06-14 8:37 ` Petr Mladek 2022-06-14 8:37 ` Petr Mladek
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