From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Bjorn Helgaas <helgaas@kernel.org>, Daniel Axtens <dja@axtens.net>
Cc: linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org,
gabriele.paoloni@huawei.com, airlied@linux.ie,
will.deacon@arm.com, dri-devel@lists.freedesktop.org,
z.liuxinliang@hisilicon.com, bhelgaas@google.com,
alex.williamson@redhat.com, lukas@wunner.de,
catalin.marinas@arm.com, zourongrong@gmail.com,
daniel.vetter@intel.com
Subject: Re: [PATCH v2 1/1] Split VGA default device handler out of VGA arbiter
Date: Sun, 20 Aug 2017 12:08:20 -0700 [thread overview]
Message-ID: <1503256100.12059.13.camel@kernel.crashing.org> (raw)
In-Reply-To: <20170819154753.GQ28977@bhelgaas-glaptop.roam.corp.google.com>
On Sat, 2017-08-19 at 10:47 -0500, Bjorn Helgaas wrote:
> So if ARM64 doesn't have these PCI legacy resources, does that mean an
> ARM64 host bridge cannot generate these legacy addresses on PCI? That
> is, there's no host bridge window that maps to those PCI addresses?
> That seems like a curious restriction on host bridges, but I guess it
> would be possible.
It's rather common. For example on POWER8:
- There is no IO space at all
- We configure the 32-bit MMIO window to be around 3..4G (to avoid
overlapping with DMA space below it).
So we effectively have no path to the legacy areas, and that hasn't
been a problem so far.
Cheers,
Ben.
next prev parent reply other threads:[~2017-08-20 19:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-17 11:30 [PATCH v2 0/1] Split VGA default nomination out from VGA arbiter Daniel Axtens
2017-08-17 11:30 ` [PATCH v2 1/1] Split VGA default device handler out of " Daniel Axtens
2017-08-18 7:38 ` Daniel Vetter
2017-08-19 15:47 ` Bjorn Helgaas
2017-08-20 19:08 ` Benjamin Herrenschmidt [this message]
2017-08-20 21:54 ` Bjorn Helgaas
2017-08-21 10:53 ` Lorenzo Pieralisi
2017-08-22 22:19 ` Bjorn Helgaas
2017-08-23 13:48 ` Ard Biesheuvel
2017-08-23 13:57 ` Bjorn Helgaas
2017-08-24 0:57 ` Dave Airlie
2017-08-24 9:38 ` Ard Biesheuvel
2017-08-24 13:57 ` Bjorn Helgaas
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