Re: console issue since 3.6, console=ttyS1 hangs

[Sean Young]

On Wed, Oct 26, 2016 at 01:16:16PM -0500, Nathan Zimmer wrote:
> On 10/25/2016 03:41 PM, Sean Young wrote:
> >On Mon, Oct 24, 2016 at 04:49:25PM -0500, Nathan Zimmer wrote:
> >>[    1.565062] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
> >The isa probe driver find the serial port.
> >
> >>[    1.566453] serial 00:04: pnp_assign_resources, try dependent set 0
> >>[    1.567383] serial 00:04:   couldn't assign io 0 (min 0x2f8 max 0x2f8)
> >But then decides that the port is already in use (the existing serial driver).
> >>[    1.568366] serial 00:04: pnp_assign_resources failed (-16)
> >>[    1.569188] serial 00:04: unable to assign resources
> >>[    1.569924] serial: probe of 00:04 failed with error -16
> >Please try and boot 3.7.0 with "8250.share_irqs=1", maybe it will pick
> >irq 3 and it will be happy again, but that is just a guess.
> >
> >I think I have not fully understood what the failure is. Does the serial
> >port not work or does the boot hang? What are the symptoms?
> With console=ttyS1 the boot will "hang", sometimes it makes it all the way
> through but may take 30 minutes, instead of the 2-4 minutes this box

Where does it hang? Any error messages?

> >We might be able to fix the problem with a pnp quirk but 3.7 is has not had
> >any releases for a long time. We will need a reproduction on a concurrent
> >kernel so a patch can be written for that.
> Yes it still happens with 4.8+
> I had only started dwelling on 3.6/3.7 since that is where it first appears
> and don't have any attachment to those.

Ok. Please try to following patch. I'm not sure it is good enough to be
merged as-is, but should provide a start for testing. Output with
CONFIG_PNP_DEBUG_MESSAGES should show only irq 3 is available for the 
serial port now.

Sean