From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vineet Gupta Date: Thu, 7 Jan 2021 09:58:05 -0800 Subject: [Buildroot] ARC no console output (was Re: [PATCH 1/2] init/console: Use ttynull as a fallback when there is no console) In-Reply-To: References: <20201111135450.11214-1-pmladek@suse.com> <20201111135450.11214-2-pmladek@suse.com> <8735zdm86m.fsf@jogness.linutronix.de> <50ade852-c598-6476-1f4b-9a3f8d11d143@synopsys.com> Message-ID: <466644f5-bed7-caef-9fcd-e66208f65545@synopsys.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net On 1/7/21 9:04 AM, Petr Mladek wrote: > On Thu 2021-01-07 08:43:16, Vineet Gupta wrote: >> Hi John, >> >> On 1/7/21 1:02 AM, John Ogness wrote: >>> Hi Vineet, >>> >>> On 2021-01-06, Vineet Gupta wrote: >>>> This breaks ARC booting (no output on console). >>> >>> Could you provide the kernel boot arguments that you use? This series is >>> partly about addressing users that have used boot arguments that are >>> technically incorrect (even if had worked). Seeing the boot arguments of >>> users that are not experiencing problems may help to reveal some of the >>> unusual console usages until now. >> >> >> Kernel command line: earlycon=uart8250,mmio32,0xf0005000,115200n8 >> console=ttyS0,115200n8 debug print-fatal-signals=1 > > This is strange, the problematic patch should use ttynull > only as a fallback. It should not be used when a particular console > is defined on the command line. What happens in my case is console_on_rootfs() doesn't find /dev/console and switching to ttynull. /dev is not present because devtmpfs doesn't automount for initramfs. > The only explanation would be that ttyS0 gets registered too late > and ttynull is added as a fallback in the meantime. I don't know if ttyS0 console should have registered already but even if it did - the /dev node missing would not have helped ? > > Anyway, I propose the revert the problematic patch for 5.11-rc3, > see > https://lore.kernel.org/lkml/20210107164400.17904-2-pmladek at suse.com/ > This mystery is a good reason to avoid bigger changes at this stage. > > Best Regards, > Petr >