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From: "Menon, Ranjit" <ranjit.menon@intel.com>
To: Tal Shnaiderman <talshn@nvidia.com>,
	Narcisa Ana Maria Vasile <navasile@linux.microsoft.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	NBU-Contact-Thomas Monjalon <thomas@monjalon.net>,
	"pallavi.kadam@intel.com" <pallavi.kadam@intel.com>,
	"dmitry.kozliuk@gmail.com" <dmitry.kozliuk@gmail.com>,
	"harini.ramakrishnan@microsoft.com"
	<harini.ramakrishnan@microsoft.com>
Subject: Re: [dpdk-dev] [PATCH] bus/pci: support segment value as address domain on Windows
Date: Thu, 10 Sep 2020 10:21:50 -0700
Message-ID: <0897c65e-a90c-e02e-e1f4-44a28993615f@intel.com> (raw)
In-Reply-To: <BY5PR12MB4323E9BFD579BD644F03B66CA4270@BY5PR12MB4323.namprd12.prod.outlook.com>


On 9/10/2020 12:30 AM, Tal Shnaiderman wrote:
>> Subject: Re: [PATCH] bus/pci: support segment value as address domain on
>> Windows
>>
>> On Tue, Aug 25, 2020 at 02:43:16PM +0300, Tal Shnaiderman wrote:
>>> Set the domain value for rte_pci_addr probing on Windows to the value
>>> of the PCI segment returned by SPDRP_BUSNUMBER.
>>>
>>> Signed-off-by: Tal Shnaiderman <talshn@nvidia.com>
>>> ---
>>>   drivers/bus/pci/windows/pci.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/bus/pci/windows/pci.c
>>> b/drivers/bus/pci/windows/pci.c index 489aa7902a..a40acec609 100644
>>> --- a/drivers/bus/pci/windows/pci.c
>>> +++ b/drivers/bus/pci/windows/pci.c
>>> @@ -195,8 +195,8 @@ get_device_pci_address(HDEVINFO dev_info,
>>>   		return -1;
>>>   	}
>>>
>>> -	addr->domain = 0;
>>> -	addr->bus = bus_num;
>>> +	addr->domain = bus_num >> 8;
>>> +	addr->bus = bus_num & 0xff;
>>>   	addr->devid = dev_and_func >> 16;
>>>   	addr->function = dev_and_func & 0xffff;
>>>   	return 0;
>>> --
>> Is this needed to avoid collision of devices with the same B:D:F?
> Right, it can happen in virtualization setups when several virtual functions can have the same BDF, e.g.:
>
> PS  > Get-NetAdapterHardwareInfo
>
> Name                           Segment Bus Device Function Slot NumaNode PcieLinkSpeed
> ----                           ------- --- ------ -------- ---- -------- -------------
> Ethernet                                   0   0     10       0                      Unknown
> Ethernet 4                       58601   0      2        0             0       Unknown
> Ethernet 5                       52956   0      2        0             0       Unknown
>
> DPDK currently can detect either Ethernet 4 or ethernet 5 if only BDF is checked.
> Unix uses the Domain value, the equivalent value for Windows is Segment.

Thanks for the explanation, Tal.

I had always been curious how Windows stores the PCIe segment (domain) 
number.

On VMs hosted on Hyper-V, the VF segment numbers are always in the high 
16-bit values.

Is this documented somewhere, or did you find this by experimentation?


ranjit m.


  reply	other threads:[~2020-09-10 17:22 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-25 11:43 Tal Shnaiderman
2020-09-09 23:21 ` Narcisa Ana Maria Vasile
2020-09-10  7:30   ` Tal Shnaiderman
2020-09-10 17:21     ` Menon, Ranjit [this message]
2020-09-13 14:50       ` Tal Shnaiderman
2020-09-10 17:57     ` Dmitry Kozlyuk
2020-09-13 14:54       ` Tal Shnaiderman
2020-09-16 18:32 ` Ranjit Menon
2020-10-14  9:01   ` Thomas Monjalon

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