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From: Arnd Bergmann <arnd@kernel.org>
To: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Sherry Sun <sherry.sun@nxp.com>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	"lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
	"arnd@arndb.de" <arnd@arndb.de>,
	"jdmason@kudzu.us" <jdmason@kudzu.us>,
	"dave.jiang@intel.com" <dave.jiang@intel.com>,
	"allenbh@gmail.com" <allenbh@gmail.com>,
	"tjoseph@cadence.com" <tjoseph@cadence.com>,
	Rob Herring <robh@kernel.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-ntb@googlegroups.com" <linux-ntb@googlegroups.com>
Subject: Re: [PATCH v7 15/18] NTB: Add support for EPF PCI-Express Non-Transparent Bridge
Date: Tue, 10 Nov 2020 15:59:08 +0100	[thread overview]
Message-ID: <CAK8P3a38vBXbAWE09H+TSoZUTkFdYDcQmXX97foT4qXQc8t5ZQ@mail.gmail.com> (raw)
In-Reply-To: <30c8f7a1-baa5-1eb4-d2c2-9a13be896f0f@ti.com>

On Tue, Nov 10, 2020 at 3:20 PM Kishon Vijay Abraham I <kishon@ti.com> wrote:
> On 10/11/20 7:55 am, Sherry Sun wrote:

> > But for VOP, only two boards are needed(one board as host and one board as card) to realize the
> > communication between the two systems, so my question is what are the advantages of using NTB?
>
> NTB is a bridge that facilitates communication between two different
> systems. So it by itself will not be source or sink of any data unlike a
> normal EP to RP system (or the VOP) which will be source or sink of data.
>
> > Because I think the architecture of NTB seems more complicated. Many thanks!
>
> yeah, I think it enables a different use case all together. Consider you
> have two x86 HOST PCs (having RP) and they have to be communicate using
> PCIe. NTB can be used in such cases for the two x86 PCs to communicate
> with each other over PCIe, which wouldn't be possible without NTB.

I think for VOP, we should have an abstraction that can work on either NTB
or directly on the endpoint framework but provide an interface that then
lets you create logical devices the same way.

Doing VOP based on NTB plus the new NTB_EPF driver would also
work and just move the abstraction somewhere else, but I guess it
would complicate setting it up for those users that only care about the
simpler endpoint case.

      Arnd

  reply	other threads:[~2020-11-10 14:59 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-30 15:35 [PATCH v7 00/18] Implement NTB Controller using multiple PCI EP Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 01/18] Documentation: PCI: Add specification for the *PCI NTB* function device Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 02/18] PCI: endpoint: Make *_get_first_free_bar() take into account 64 bit BAR Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 03/18] PCI: endpoint: Add helper API to get the 'next' unreserved BAR Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 04/18] PCI: endpoint: Make *_free_bar() to return error codes on failure Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 05/18] PCI: endpoint: Remove unused pci_epf_match_device() Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 06/18] PCI: endpoint: Add support to associate secondary EPC with EPF Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 07/18] PCI: endpoint: Add support in configfs to associate two EPCs " Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 08/18] PCI: endpoint: Add pci_epc_ops to map MSI irq Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 09/18] PCI: endpoint: Add pci_epf_ops for epf drivers to expose function specific attrs Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 10/18] PCI: endpoint: Allow user to create sub-directory of 'EPF Device' directory Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 11/18] PCI: cadence: Implement ->msi_map_irq() ops Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 12/18] PCI: cadence: Configure LM_EP_FUNC_CFG based on epc->function_num_map Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 13/18] PCI: endpoint: Add EP function driver to provide NTB functionality Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 14/18] PCI: Add TI J721E device to pci ids Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 15/18] NTB: Add support for EPF PCI-Express Non-Transparent Bridge Kishon Vijay Abraham I
2020-11-09  9:37   ` Sherry Sun
2020-11-09 14:21     ` Kishon Vijay Abraham I
2020-11-10  2:25       ` Sherry Sun
2020-11-10 14:20         ` Kishon Vijay Abraham I
2020-11-10 14:59           ` Arnd Bergmann [this message]
2020-11-10 15:42             ` Kishon Vijay Abraham I
2020-11-11  2:49               ` Sherry Sun
2020-11-12 11:12                 ` Kishon Vijay Abraham I
2020-11-12 12:35                   ` Sherry Sun
2020-11-12 13:24               ` Arnd Bergmann
2020-11-16  5:19                 ` Kishon Vijay Abraham I
2020-11-16 15:37                   ` Arnd Bergmann
2020-11-16 15:45                     ` Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 16/18] NTB: tool: Enable the NTB/PCIe link on the local or remote side of bridge Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 17/18] Documentation: PCI: Add configfs binding documentation for pci-ntb endpoint function Kishon Vijay Abraham I
2020-09-30 15:35 ` [PATCH v7 18/18] Documentation: PCI: Add userguide for PCI endpoint NTB function Kishon Vijay Abraham I
2020-10-05  5:57 ` [PATCH v7 00/18] Implement NTB Controller using multiple PCI EP Kishon Vijay Abraham I
2020-10-20  8:15   ` Kishon Vijay Abraham I
2020-10-20 13:18     ` Lorenzo Pieralisi
2020-11-03  7:58       ` Kishon Vijay Abraham I

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