Re: [RFC][PATCH] Way for platforms to alter built-in serial ports

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Wednesday 06 October 2004 1:32 am, Russell King wrote:
> On Fri, Oct 01, 2004 at 08:58:27AM -0600, Bjorn Helgaas wrote:
> > My main point is that I think the early init stuff (i.e.,
> > serial8250_isa_init_ports()) should go away, so we don't have the
> > dichotomy of having the compiled-in stuff handled differently than
> > the run-time enumerated stuff.
> 
> You're always going to have this.  For instance, the standard ISA serial
> ports may not show up in any "enumerated stuff" on an x86 box - and x86
> people expect that the port at 0x3f8 is ttyS0, 2f8 is ttyS1 etc.
> 
> Change that order and they'll scream at you.

I don't forsee any order changing.  I would expect to use link
ordering so all the 8250_platform ports are registered first, then
all the 8250_acpi, then all the 8250_pci.

The order WOULD change in some cases on ia64, because we'd get rid
of the current wierdness where the device in the HCDP/PCDP firmware
table always becomes ttyS0, regardless of where it lives.  This
would be an improvement, though, because the devices would stop
changing names just because you selected a different firmware
console.

> See my previous mail why this doesn't work - x86 serial console
> requirements.
> 
> I think you'll do better to discuss this problem with Alan so that
> he can change his (and maybe others) points of view wrt when the
> serial console is initialised.  Until then I'm going to continue
> sitting on the fence on this point.

Yeah, I'll poke him about "console=uart".  I sent it to you because I
think a clean solution requires minor 8250 hooks so we can look up
the ttyS device that corresponds to an MMIO or IO address.