Re: console issue since 3.6, console=ttyS1 hangs

From	Sean Young <sean@mess.org>
Newsgroups	linux.kernel
Subject	Re: console issue since 3.6, console=ttyS1 hangs
Date	2016-10-18 20:10 +0200
Message-ID	<stGZP-5pH-5@gated-at.bofh.it> (permalink)
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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.

Sean

Thread

console issue since 3.6, console=ttyS1 hangs Nathan Zimmer <nzimmer@sgi.com> - 2016-10-17 17:00 +0200
  Re: console issue since 3.6, console=ttyS1 hangs Sean Young <sean@mess.org> - 2016-10-17 17:20 +0200
    Re: console issue since 3.6, console=ttyS1 hangs Nathan Zimmer <nzimmer@sgi.com> - 2016-10-17 18:50 +0200
      Re: console issue since 3.6, console=ttyS1 hangs Nathan Zimmer <nzimmer@sgi.com> - 2016-10-18 18:50 +0200
        Re: console issue since 3.6, console=ttyS1 hangs Sean Young <sean@mess.org> - 2016-10-18 20:10 +0200
          Re: console issue since 3.6, console=ttyS1 hangs Sean Young <sean@mess.org> - 2016-10-19 17:10 +0200
            Re: console issue since 3.6, console=ttyS1 hangs Nathan Zimmer <nzimmer@sgi.com> - 2016-10-20 00:20 +0200
              Re: console issue since 3.6, console=ttyS1 hangs Sean Young <sean@mess.org> - 2016-10-20 22:20 +0200
                Re: console issue since 3.6, console=ttyS1 hangs Nathan Zimmer <nzimmer@sgi.com> - 2016-10-21 18:00 +0200
                Re: console issue since 3.6, console=ttyS1 hangs Sean Young <sean@mess.org> - 2016-10-24 16:00 +0200
                Re: console issue since 3.6, console=ttyS1 hangs Sean Young <sean@mess.org> - 2016-10-25 22:50 +0200
                Re: console issue since 3.6, console=ttyS1 hangs Nathan Zimmer <nzimmer@sgi.com> - 2016-10-26 20:20 +0200

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