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Re: [Qemu-devel] [PATCH 1/4] Split serial-isa into its own config option


From: David Gibson
Subject: Re: [Qemu-devel] [PATCH 1/4] Split serial-isa into its own config option
Date: Wed, 1 Jul 2015 14:20:37 +1000
User-agent: Mutt/1.5.23 (2014-03-12)

On Mon, Jun 29, 2015 at 11:35:23AM +0100, Peter Maydell wrote:
> On 29 June 2015 at 06:36, David Gibson <address@hidden> wrote:
> > At present, the core device model code for 8250-like serial ports
> > (serial.c) and the code for serial ports attached to ISA-style legacy IO
> > (serial-isa.c) are both controlled by the CONFIG_SERIAL variable.
> >
> > There are lots and lots of embedded platforms that have 8250-like serial
> > ports but have never had anything resembling ISA legacy IO.  Therefore,
> > split serial-isa into its own CONFIG_SERIAL_ISA option so it can be
> > disabled for platforms where it's not appropriate.
> >
> > For now, I enabled CONFIG_SERIAL_ISA in every default-config where
> > CONFIG_SERIAL is enabled, excepting microblaze, xtensa and or32.  Those
> > platforms have technically lost functionality, but since they have no
> > other PCI or ISA devices, it's fairly clear they never actually used
> > leagacy IO stuff.
> 
> s/leagacy/legacy/
> 
> Is it worth having a default-configs/isa.mak along the
> lines of our current pci.mak and usb.mak, for putting
> CONFIG_ defines for all ISA devices?
> 
> A quick grep suggests you can knock arm, moxie, sh4
> and sh4eb off your list of things with CONFIG_SERIAL_ISA
> (no hits for ISABus).

I'll remove moxie, sh4 and sh4eb in my next spin.

I'm not so comfortable about ARM.  I get the impression that there are
so many x86 people now working in the ARM space, that it wouldn't
surprise me at all if some vendors go and stick legacy stuff on
there.  So I'd prefer to leave it to the ARM people themselves to turn
it off if I'm wrong.

> I notice in passing that we still have a handful of config
> files which set CONFIG_ISA_MMIO, despite that having been
> deleted in commit 61fcb628627ea4 two years ago.

Hm, I'll add a patch to clean that up, why not.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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