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Message-ID: <11716372.n451O5j8Vs@wuerfel>
Date: Fri, 18 Nov 2016 10:22:46 +0100
From: Arnd Bergmann <arnd@...db.de>
To: linux-arm-kernel@...ts.infradead.org
Cc: One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
Mark Rutland <mark.rutland@....com>,
gabriele.paoloni@...wei.com, benh@...nel.crashing.org,
will.deacon@....com, linuxarm@...wei.com,
lorenzo.pieralisi@....com, xuwei5@...ilicon.com,
linux-serial@...r.kernel.org, catalin.marinas@....com,
devicetree@...r.kernel.org, minyard@....org, marc.zyngier@....com,
liviu.dudau@....com, john.garry@...wei.com, zourongrong@...il.com,
robh+dt@...nel.org, bhelgaas@...gle.com, kantyzc@....com,
zhichang.yuan02@...il.com, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org,
"zhichang.yuan" <yuanzhichang@...ilicon.com>, olof@...om.net
Subject: Re: [PATCH V5 2/3] ARM64 LPC: Add missing range exception for special ISA
On Monday, November 14, 2016 11:11:11 AM CET One Thousand Gnomes wrote:
> > > It's not a safe assumption for x86 at least. There are a few systems with
> > > multiple ISA busses particularly older laptops with a docking station.
> >
> > But do they have multiple ISA domains? There is no real harm in supporting
> > it, the (small) downsides I can think of are:
>
> I don't believe they x86 class ones have multiple ISA domains. But as
> I've said I don't know how the electronics in the older ThinkPad worked
> when it used two PIIX4s with some LPC or ISA stuff on each.
>
> It works in DOS and unmodified Linux so I'm pretty sure there are no
> additional domains. Likewise the various x86 schemes that route some bits
> of ISA bus off into strange places work in DOS and don't have any
> overlaps.
>
> yenta_socket handles PCI/PCMCIA bridging and routes a range of that flat
> ISA space appropriately to the card.
Right, that's what I had expected, so we still don't even
need to handle multiple ISA I/O address spaces for the
only known case of multiple ISA buses, though we may decide
to generalize the code like that anyway.
Arnd
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