From: matthew.gerlach@linux.intel.com
To: Russ Weight <russell.h.weight@intel.com>
Cc: Tom Rix <trix@redhat.com>,
hao.wu@intel.com, yilun.xu@intel.com,
basheer.ahmed.muddebihal@intel.com, mdf@kernel.org,
corbet@lwn.net, linux-fpga@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
dan.j.williams@intel.com, ashok.raj@intel.com,
tianfei.zhang@intel.com
Subject: Re: [PATCH v2 1/2] Documentation: fpga: dfl: add PCI Identification documentation
Date: Fri, 4 Mar 2022 10:30:47 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2203041021240.3408681@rhweight-WRK1> (raw)
In-Reply-To: <bc41bc12-0d88-771f-7e78-4e29361fcfd8@intel.com>
[-- Attachment #1: Type: text/plain, Size: 3691 bytes --]
On Fri, 4 Mar 2022, Russ Weight wrote:
>
>
> On 3/3/22 14:04, Tom Rix wrote:
>>
>> On 3/2/22 4:35 PM, matthew.gerlach@linux.intel.com wrote:
>>> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>>>
>>> Add documentation on identifying FPGA based PCI cards prompted
>>> by discussion on the linux-fpga@vger.kernel.org mailing list.
>>>
>>> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>>> ---
>>> v2: Introduced in v2.
>>> ---
>>> Documentation/fpga/dfl.rst | 20 ++++++++++++++++++++
>>> 1 file changed, 20 insertions(+)
>>>
>>> diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
>>> index ef9eec71f6f3..5fb2ca8e76d7 100644
>>> --- a/Documentation/fpga/dfl.rst
>>> +++ b/Documentation/fpga/dfl.rst
>>> @@ -502,6 +502,26 @@ Developer only needs to provide a sub feature driver with matched feature id.
>>> FME Partial Reconfiguration Sub Feature driver (see drivers/fpga/dfl-fme-pr.c)
>>> could be a reference.
>>> +PCI Device Identification
>>> +================================
>>> +Since FPGA based PCI cards can be reconfigured to a perform a completely
>>> +new function at runtime, properly identifying such cards and binding the
>>> +correct driver can be challenging. In many use cases, deployed FPGA based
>>> +PCI cards are essentially static and the PCI Product ID and Vendor ID pair
>>> +is sufficient to identify the card. The DFL framework helps with the
>>> +dynamic case of deployed FPGA cards changing at run time by providing
>>> +more detailed information about card discoverable at runtime.
>>> +
>>> +At one level, the DFL on a PCI card describes the function of the card.
>>> +However, the same DFL could be instantiated on different physical cards.
>>> +Conversely, different DFLs could be instantiated on the same physical card.
>>> +Practical management of a cloud containing a heterogeneous set of such cards
>>> +requires a PCI level of card identification. While the PCI Product ID and
>>> +Vendor ID may be sufficient to bind the dfl-pci driver, it is expected
>>> +that FPGA PCI cards would advertise suitable Subsystem ID and Subsystem
>>> +Vendor ID values. PCI Vital Product Data (VPD) can also be used for
>>> +more granular information about the board.
>>
>> This describes a bit more of the problem, it should describe it wrt ofs dev id. The introduction of the ofs dev should be explicitly called out as a generic pci id.
The problem I'm describing exists for all FPGA based PCI cards; so I am
purposely trying to be abstract as much as possible.
>>
>> Why couldn't one of the old pci id's be reused ?
Yes, old pci id's could be reused, and people have done just that. We
thought a new PCI ID would minimize confusion with cards that have already
been deployed.
>>
>> How will the subvendor/subid be enforced ?
Subvendor and Subid are managed just like any other PCI card with or
without a FPGA.
>>
>> Is the current security manager patchset smart enough to save the board from being bricked when a user doesn't look beyond the pci id ?
>
> Yes - the security manager is invoked based of DFL feature ID and revision, and the functionality is differentiated based on the same information.
>
>>
>> What happens if a board uses this device id but doesn't have a max10 to do the update ?
If a board doesn't have a max10, then there will be no DFH for a max10 in
the board's DFLs. Presumeably, the board would need some update process,
and an approprate DFH would be in that board's DFL.
>>
>> Tom
>>
>>> +
>>> Location of DFLs on a PCI Device
>>> ================================
>>> The original method for finding a DFL on a PCI device assumed the start of the
>>
>
>
next prev parent reply other threads:[~2022-03-04 18:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-03 0:35 [PATCH v2 0/2] Add PCIE device IDs for Intel DFL cards matthew.gerlach
2022-03-03 0:35 ` [PATCH v2 1/2] Documentation: fpga: dfl: add PCI Identification documentation matthew.gerlach
2022-03-03 22:04 ` Tom Rix
2022-03-04 16:45 ` Russ Weight
2022-03-04 18:30 ` matthew.gerlach [this message]
2022-03-22 17:11 ` Tom Rix
2022-03-11 4:16 ` Wu, Hao
2022-03-03 0:35 ` [PATCH v2 2/2] drivers: fpga: dfl-pci: Add PCIE device IDs for Intel DFL cards matthew.gerlach
2022-03-11 4:20 ` Wu, Hao
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