From: "Veal, Bryan E." <bryan.e.veal@intel.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Keith Busch <keith.busch@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, linux-pci@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Bjorn Helgaas <bhelgaas@google.com>,
Dan Williams <dan.j.williams@intel.com>,
Jon Derrick <jonathan.derrick@intel.com>
Subject: Re: [PATCHv8 0/5] Driver for new "VMD" device
Date: Fri, 15 Jan 2016 11:31:03 -0800 [thread overview]
Message-ID: <20160115193103.GA2249@intel.com> (raw)
In-Reply-To: <20160115181938.GA5296@localhost>
On Fri, Jan 15, 2016 at 12:19:38PM -0600, Bjorn Helgaas wrote:
> I also have a more substantive question about the flags setup. I
> think you should not clear IORESOURCE_MEM_64. The intent of
> IORESOURCE_MEM_64 is to describe the *capability* of a BAR, not its
> contents. But I assume you cleared it for a reason. vmd->resources[n]
> are not BARs, so the PCI core won't assign resources to them like it
> does for BAR, so we shouldn't care about IORESOURCE_MEM_64 for that
> reason. Is there some other reason IORESOURCE_MEM_64 makes a
> difference there?
Hi Bjorn & Keith:
I did this to fix an issue in pre-RFC code.
The flag is subtly restrictive in one specific scenario: spec-compliant
PCIe ports lack the ability to specify a 64-bit, non-prefetchable range.
IORESOURCE_MEM_64 directs the PCI subsystem to put the address into the
64-bit *prefetchable* range. Below the port, the "prefetchable" propoerty
*is* restrictive: the addresses can't be used for non-prefetchable BARs.
Thus, in the specific case where a 64-bit non-prefetchable VMD bar happens
to contain a 32-bit address, removing the IORESOURCE_MEM_64 flag allows
the address resource to be used for *any* non-prefetchable BARs (32-bit or
64-bit) downstream.
next prev parent reply other threads:[~2016-01-15 19:30 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-12 20:18 [PATCHv8 0/5] Driver for new "VMD" device Keith Busch
2016-01-12 20:18 ` [PATCHv8 1/5] msi: Relax msi_domain_alloc() to support parentless MSI irqdomains Keith Busch
2016-01-12 20:18 ` [PATCHv8 2/5] x86/IRQ: Export IRQ domain function for module use Keith Busch
2016-01-12 20:18 ` [PATCHv8 3/5] x86/PCI: Allow PCI domain specific dma ops Keith Busch
2016-01-12 20:18 ` [PATCHv8 4/5] PCI/AER: Use 32 bit int type domains Keith Busch
2016-01-12 20:18 ` [PATCHv8 5/5] x86/PCI: Initial commit for new VMD device driver Keith Busch
2016-01-15 18:19 ` [PATCHv8 0/5] Driver for new "VMD" device Bjorn Helgaas
2016-01-15 19:31 ` Veal, Bryan E. [this message]
2016-01-15 21:49 ` Bjorn Helgaas
2016-01-16 22:19 ` Veal, Bryan E.
2016-01-20 22:01 ` Bjorn Helgaas
2016-02-22 22:10 ` Bjorn Helgaas
2016-02-23 18:24 ` Keith Busch
2016-02-25 14:42 ` Bjorn Helgaas
2016-02-25 14:50 ` Keith Busch
2016-02-26 15:29 ` Keith Busch
2016-01-15 19:32 ` Keith Busch
2016-01-15 19:44 ` Thomas Gleixner
2016-01-15 20:03 ` Bjorn Helgaas
2016-01-15 20:14 ` Thomas Gleixner
2016-01-15 19:48 ` Derrick, Jonathan
2016-01-15 19:54 ` Keith Busch
2016-01-15 20:02 ` Jon Derrick
2016-01-15 22:06 ` Bjorn Helgaas
2016-01-19 15:38 ` Keith Busch
2016-01-19 16:02 ` Christoph Hellwig
2016-01-19 16:36 ` Keith Busch
2016-01-19 22:05 ` Veal, Bryan E.
2016-01-20 20:43 ` Bjorn Helgaas
2016-01-26 16:46 ` Christoph Hellwig
2016-01-26 18:23 ` Veal, Bryan E.
2016-01-17 17:58 ` Christoph Hellwig
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