linux-kernel - Re: 2.6.24: Serial disabled in BIOS but serial modules still loaded (probably PnP related)

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Message-Id: <1195962922.5044.8.camel@canyon.wittsend.com>
Date:	Sat, 24 Nov 2007 22:55:22 -0500
From:	"Michael H. Warfield" <mhw@...tsEnd.com>
To:	Andrey Borzenkov <arvidjaar@...l.ru>
Cc:	mhw@...tsEnd.com, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: 2.6.24: Serial disabled in BIOS but serial modules still
	loaded (probably PnP related)

On Sat, 2007-11-24 at 23:36 +0300, Andrey Borzenkov wrote:
> I have no COM port on notebook (without port replicator which I do not have)
> so COM is disabled in BIOS. No ttyS* is detected during boot (and no device
> created) but I just noticed that serial modules are still loaded. Well, this
> partially defeats the purpose of disabling COM port - the intention was to
> free resources by *not* loading unneeded modules ...

> This may have something to do with (ACPI) PnP which apparently believes COM is alive.
> Notebook is Toshiba Portege 4000.

	Nice...  What's this then?

> 00:09 PNP0501 16550A-compatible serial port
>     state = active
>         io 0x3f8-0x3ff
>         irq 5

	0x3f8-0x3ff is COM1 and a 16550A is the most common invocation of the
vernerable serial port.  I haven't seen a real 8250 in ages.  the 16550
is an 8250 with larger FIFO's and better rates.

	Now, it's on IRQ5 instead of IRQ4 but that's all allocatable on PCI.
Unless I'm missing something, it looks like you've got a COM port and it
looks like it's active.

	Might be related to an IR port?

> 00:0a SMCf010 SMC Fast Infrared Port
>     state = disabled

> 00:0b PNP0401 ECP printer port
>     state = disabled

	:

	Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw@...tsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
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