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SubjectRe: PnP model
On Tue, 4 Feb 2003, Russell King wrote:

> On Mon, Feb 03, 2003 at 08:43:25PM +0000, Adam Belay wrote:
> > In many cases, Auto configuration can be better then manual configuration.
> > 1.) The auto configuration engine in my patch is able to resolve almost any
> > resource conflict and provides the greatest chance for all devices to have
> > resources allocated.
> There is a nice problem with ISA PNP serial ports generated by this
> type of thing in 2.5.59.
> On boot, we probe for the usual serial ports, and discover two at
> 0x3f8 and 0x2f8, and we request these resources. Please note that
> one port could be in use as a serial console from earlier in the
> bootup.
> Then, we move on to the PNP probes. The PNP layer gives us two
> serial ports, and we initialise them. The PNP layer notices that
> the resources for 0x3f8 and 0x2f8, and re-assigns the ports to
> 0x3e8 and 0x2e8. The serial layer finds two extra ports at
> 0x3e8 and 0x2e8.
> However, the ports at 0x3f8 and 0x2f8 are now gone, along with the
> serial console, and the boot messages claim that we have four serial
> ports at ttyS0, ttyS1, ttyS2, and ttyS3, when the machine in fact
> only has two serial ports. The serial layer likewise believes we
> have four serial ports.
> I look forward to your thoughts on getting around this problem.

I think that legacy devices must be probed after PnP ones, otherwise
you'll get these duplications.


Jaroslav Kysela <>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs

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