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From: Bjorn Helgaas <helgaas@kernel.org>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: "Jens Axboe" <axboe@kernel.dk>,
	linux-block@vger.kernel.org,
	"Alex Williamson" <alex.williamson@redhat.com>,
	linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvme@lists.infradead.org,
	"Sinan Kaya" <okaya@codeaurora.org>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Jason Gunthorpe" <jgg@mellanox.com>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Max Gurtovoy" <maxg@mellanox.com>,
	"Keith Busch" <keith.busch@intel.com>,
	"Eric Wehage" <Eric.Wehage@huawei.com>,
	"Christoph Hellwig" <hch@lst.de>
Subject: Re: [PATCH v3 01/11] PCI/P2PDMA: Support peer-to-peer memory
Date: Mon, 26 Mar 2018 09:01:18 -0500	[thread overview]
Message-ID: <20180326140118.GA221690@bhelgaas-glaptop.roam.corp.google.com> (raw)
In-Reply-To: <20180326121138.00005e30@huawei.com>

On Mon, Mar 26, 2018 at 12:11:38PM +0100, Jonathan Cameron wrote:
> On Tue, 13 Mar 2018 10:43:55 -0600
> Logan Gunthorpe <logang@deltatee.com> wrote:
> > It turns out that root ports that support P2P are far less common than 
> > anyone thought. So it will likely have to be a white list.
> 
> This came as a bit of a surprise to our PCIe architect.
> 
> His follow up was whether it was worth raising an ECR for the PCIe spec
> to add a capability bit to allow this to be discovered.  This might
> long term avoid the need to maintain the white list for new devices.
> 
> So is it worth having a long term solution for making this discoverable?

It was surprising to me that there's no architected way to discover
this.  It seems like such an obvious thing that I guess I assumed the
omission was intentional, i.e., maybe there's something that makes it
impractical, but it would be worth at least asking somebody in the
SIG.  It seems like for root ports in the same root complex, at least,
there could be a bit somewhere in the root port or the RCRB (which
Linux doesn't support yet).
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  reply	other threads:[~2018-03-26 13:54 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-12 19:35 [PATCH v3 00/11] Copy Offload in NVMe Fabrics with P2P PCI Memory Logan Gunthorpe
2018-03-12 19:35 ` [PATCH v3 01/11] PCI/P2PDMA: Support peer-to-peer memory Logan Gunthorpe
2018-03-13  3:28   ` Sinan Kaya
2018-03-13 16:43     ` Logan Gunthorpe
2018-03-13 17:49       ` Sinan Kaya
2018-03-13 18:44         ` Logan Gunthorpe
2018-03-13 19:10           ` Sinan Kaya
2018-03-13 19:19             ` Logan Gunthorpe
2018-03-13 19:53               ` Sinan Kaya
2018-03-13 20:46                 ` Logan Gunthorpe
2018-03-13 21:22                   ` Sinan Kaya
2018-03-13 22:00                     ` Logan Gunthorpe
2018-03-13 22:29                       ` Sinan Kaya
2018-03-13 22:45                         ` Stephen  Bates
2018-03-13 22:48                         ` Logan Gunthorpe
2018-03-13 23:19                           ` Sinan Kaya
2018-03-13 23:45                             ` Logan Gunthorpe
2018-03-14 12:16                               ` David Laight
2018-03-14 16:23                                 ` Logan Gunthorpe
2018-03-13 22:31                       ` Stephen  Bates
2018-03-13 23:08                         ` Bjorn Helgaas
2018-03-13 23:21                           ` Logan Gunthorpe
2018-03-14  2:56                             ` Bjorn Helgaas
2018-03-14 14:05                               ` Stephen  Bates
2018-03-14 16:17                               ` Logan Gunthorpe
2018-03-14 18:51                                 ` Bjorn Helgaas
2018-03-14 19:03                                   ` Logan Gunthorpe
2018-03-14 19:28                                     ` Dan Williams
2018-03-14 19:30                                       ` Logan Gunthorpe
2018-03-14 19:34                                       ` Stephen  Bates
2018-03-15  4:00                                         ` Martin K. Petersen
2018-03-15  4:30                                         ` Dan Williams
2018-03-22 22:57                           ` Stephen  Bates
2018-03-23 21:50                             ` Bjorn Helgaas
2018-03-23 21:59                               ` Logan Gunthorpe
2018-03-24  3:49                                 ` Bjorn Helgaas
2018-03-24 15:28                                   ` Stephen  Bates
2018-03-26 15:43                                     ` Logan Gunthorpe
2018-03-26 11:11       ` Jonathan Cameron
2018-03-26 14:01         ` Bjorn Helgaas [this message]
2018-03-26 15:46           ` Logan Gunthorpe
2018-03-27  8:47             ` Jonathan Cameron
2018-03-27 15:37               ` Logan Gunthorpe
2018-04-13 21:56               ` Stephen  Bates
2018-03-26 16:41         ` Jason Gunthorpe
2018-03-26 17:30           ` Logan Gunthorpe
2018-03-26 19:35             ` Jason Gunthorpe
2018-03-26 20:42               ` Logan Gunthorpe
2018-03-13 18:40     ` Logan Gunthorpe
2018-03-12 19:35 ` [PATCH v3 02/11] PCI/P2PDMA: Add sysfs group to display p2pmem stats Logan Gunthorpe
2018-03-12 19:35 ` [PATCH v3 03/11] PCI/P2PDMA: Add PCI p2pmem dma mappings to adjust the bus offset Logan Gunthorpe
2018-03-12 19:35 ` [PATCH v3 04/11] PCI/P2PDMA: Clear ACS P2P flags for all devices behind switches Logan Gunthorpe
2018-03-12 19:35 ` [PATCH v3 05/11] PCI/P2PDMA: Add P2P DMA driver writer's documentation Logan Gunthorpe
2018-03-12 19:41   ` Jonathan Corbet
2018-03-12 21:18     ` Logan Gunthorpe
2018-03-12 19:35 ` [PATCH v3 06/11] block: Introduce PCI P2P flags for request and request queue Logan Gunthorpe
2018-03-21  9:27   ` Christoph Hellwig
2018-03-12 19:35 ` [PATCH v3 07/11] IB/core: Ensure we map P2P memory correctly in rdma_rw_ctx_[init|destroy]() Logan Gunthorpe
2018-03-21  9:27   ` Christoph Hellwig
2018-03-12 19:35 ` [PATCH v3 08/11] nvme-pci: Use PCI p2pmem subsystem to manage the CMB Logan Gunthorpe
2018-03-13  1:55   ` Sinan Kaya
2018-03-13  1:58     ` Sinan Kaya
2018-03-12 19:35 ` [PATCH v3 09/11] nvme-pci: Add support for P2P memory in requests Logan Gunthorpe
2018-03-21  9:23   ` Christoph Hellwig
2018-03-12 19:35 ` [PATCH v3 10/11] nvme-pci: Add a quirk for a pseudo CMB Logan Gunthorpe
2018-03-12 19:35 ` [PATCH v3 11/11] nvmet: Optionally use PCI P2P memory Logan Gunthorpe
2018-03-21  9:27   ` Christoph Hellwig
2018-03-21 16:52     ` Logan Gunthorpe

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