From: Bjorn Helgaas <bjorn.helgaas@hp.com>
To: Michael Mauch <michael.mauch@gmx.de>
Subject: Re: Serial ports rearranged in 2.6.22?
Date: Mon, 13 Aug 2007 16:33:56 -0600
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Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
       Yinghai Lu <yhlu.kernel@gmail.com>
References: <20070810213925.GB10855@elmicha> <200708131534.15235.bjorn.helgaas@hp.com> <20070813222800.GB25159@elmicha>
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On Monday 13 August 2007 04:28:00 pm Michael Mauch wrote:
> Bjorn Helgaas wrote:
> 
> > On Saturday 11 August 2007 09:49:25 am Michael Mauch wrote:
> > > Yinghai Lu wrote:
> > > 
> > > > On 8/10/07, Michael Mauch <michael.mauch@gmx.de> wrote:
> > > > >
> > > > > With 2.6.22 I get the names <-> ports/irqs the other way around:
> > > > >
> > > > > 00:08: ttyS0 at I/O 0x2f8 (irq = 3) is a 16550A
> > > > > 00:09: ttyS1 at I/O 0x3f8 (irq = 4) is a 16550A
> > > > > ...
> > > > http://lkml.org/lkml/2007/7/25/455
> > > 
> > > Thanks - I applied that patch and the names are back to normal again:
> > > 
> > > 00:06: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> > > 00:07: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
> > 
> > Just FYI, the patch Yinghai mentioned above was experimental, and
> > we decided it was the wrong solution.
> > 
> > For 2.6.22, the easiest workaround is to boot with the 
> > "legacy_serial.force" option.
> 
> Ah, ok, and load the legacy_serial module. Going from built-in serial to
> modules I was already challenged to find serial_core, 8250, 8250_pnp
> and/or 8250_pci (the help in "make menuconfig" does not seem to show the
> help that is written in the Kconfig file for 8250_pnp and 8250_pci).

Yes, I messed up the legacy_serial module stuff.

> > For 2.6.23, we reverted my patch that caused the names to be swapped:
> >   http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=57d4810ea0d9ca58a7bcc1336607f0cede0a2abf
> 
> Thanks for the information - I wondered how you decided. 
> 
> What about 2.6.22.x? Or should the distro kernels use that revert patch
> for their stable 2.6.22 kernels?

I would not recommend the experimental patch (http://lkml.org/lkml/2007/7/25/455).
Using the revert patch is probably safest, since it also avoids
the module load issues.

Bjorn
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