Re: ARC no console output (was Re: [PATCH 1/2] init/console: Use ttynull as a fallback when there is no console)

Sergey Senozhatsky
2021-01-08T03:49:29Z

On (21/01/07 09:58), Vineet Gupta wrote:
> 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 <vgupta@synopsys.com> 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.

I wonder if we'll move the nulltty fallback logic into printk code [1]
will it fix the problem?

[1] https://lore.kernel.org/lkml/X6x%2FAxD1qanC6evJ@jagdpanzerIV.localdomain/

-ss