Re: console issue since 3.6, console=ttyS1 hangs

[Nathan Zimmer]

On 10/19/2016 04:07 AM, Sean Young wrote:
> On Tue, Oct 18, 2016 at 02:29:30PM -0500, Nathan Zimmer wrote:
> > On Tue, Oct 18, 2016 at 07:05:18PM +0100, Sean Young wrote:
> > > On Tue, Oct 18, 2016 at 11:40:04AM -0500, Nathan Zimmer wrote:
> > > > 3.7.0
> > > > cat /sys/bus/pnp/drivers/serial/*/resources
> > > > state = active
> > > > io 0x2f8-0x2ff
> > > > irq 12
> > > > dma disabled
> > > >
> > > > 3.6.0
> > > > :~ # cat /sys/bus/pnp/drivers/serial/*/resources
> > > > cat: /sys/bus/pnp/drivers/serial/*/resources: No such file or directory
> > > irq 12 for ttyS1? That should be irq 3. The bios is putting bogus information
> > > in pnp. Maybe there is rubbish in the bios setup or maybe it's fixed in a
> > > newer bios update.
> > >
> > > So before this change, the kernel would assume irq 3. After this change,
> > > the kernel first uses the information in pnp to see where the serial
> > > port is. It gets told that it's irq 12 and presumably it runs into all
> > > sorts of problems then. If memory serves that's the irq for the ps/2 mouse.
> > >
> > > The interesting bit is in 3.6.0:
> > >
> > > setserial
> > > /dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 3
> > >
> > > becomes in 3.7.0:
> > >
> > > setserial
> > > /dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 12
> > >
> > > You should be able to set the right irq with setserial, but obviously
> > > that doesn't help you if it fails in early boot. It's not immediately
> > > obvious to me what can be done in the kernel for this. Maybe the dmesg
> > > output could inspire, thanks.
> > Yea the changing irq seemed weird to me too but I couldn't manage a guess to why.
> >
> > Here are the dmesgs.
> So with 3.6.0:
>
> > [    2.079980] Serial: 8250/16550 driver, 8 ports, IRQ sharing disabled
> > [    2.100887] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
> > [    2.101715] serial 00:04: unable to assign resources
> > [    2.102174] serial: probe of 00:04 failed with error -16
> The pnp probe fails for some reason. I don't understand why.
>
> With 3.7.0:
>
> > [    2.062700] Serial: 8250/16550 driver, 8 ports, IRQ sharing disabled
> > [    2.063250] serial 00:04: [io  0x02f8-0x02ff]
> > [    2.063875] serial 00:04: [irq 12]
> > [    2.064345] serial 00:04: [dma 18446744073709551615 disabled]
> > [    2.065540] serial 00:04: activated
> > [    2.086442] 00:04: ttyS1 at I/O 0x2f8 (irq = 12) is a 16550A
> Now the pnp probe succeeds (with broken irq from pnp).
>
> Can you please check if there is a wrong irq configured in the bios setup
> or if there is a bios update available? I don't know why this worked in
> the first place.
>
>
> Sean

Apparently this is the latest bios available for these nodes.
Also in the bios setup screens I don't see anything for changing irq 
numbers for serial console.
But this is a cluster so sometimes thing get hidden to keep everything 
uniform as possible.

If you want to point me to the pnp probe code you would be suspicious of 
I can try to debug and see what is going there.