Re: [PATCH v3] console: use first console if stdout-path device doesn't appear

[Larry Finger]

On 11/07/2016 03:18 AM, Paul Burton wrote:
> On Monday, 7 November 2016 19:27:32 GMT Michael Ellerman wrote:
> > Paul Burton <paul.burton@xxxxxxxxxx> writes:
> > > If a device tree specified a preferred device for kernel console output
> > > via the stdout-path or linux,stdout-path chosen node properties there's
> > > no guarantee that it will have specified a device for which we have a
> > > driver. It may also be the case that we do have a driver but it doesn't
> > > call of_console_check() to register as a preferred console (eg. offb
> > > driver as used on powermac systems).
> > >
> > > In these cases try to ensure that we provide some console output by
> > > enabling the first usable registered console, which we keep track of
> > > with the of_fallback_console variable. Affected systems will enable
> > > their console later than they did prior to commit 05fd007e4629
> > > ("console: don't prefer first registered if DT specifies stdout-path")
> > > but should otherwise produce the same output.
> > >
> > > Tested in QEMU with a PowerPC pseries_defconfig kernel.
> >
> > Hi Paul,
> >
> > This does "work", as in it boots and I get a console. But the delay in
> > getting output on the VGA is not workable. I get pretty much no output
> > until the machine is booted entirely to userspace, meaning any crash
> > prior to that will be undebuggable.
> >
> > I also note Andreas reports it doesn't work at all on PowerMac.
> >
> > Please send a revert and we can try again next cycle.
> >
> > cheers
>
> Hi Michael,
>
> A revert was already submitted by Hans de Goede & is being discussed over
> here:
>
> https://marc.info/?l=linux-kernel&m=147826151427455&w=2

I am a little surprised that I was not CCd on that thread. To reiterate, my 
PowerBook G4 with a PPC32 processor CRASHES on boot. That is a lot more serious 
than the console output disappearing.

As it seems unlikely that this regression will be fixed in the current cycle, I 
recommend that the reversion of commit 05fd007e4629 until a proper fix is available.

Larry