Messages in this thread | | | Date | Wed, 26 Jun 2013 14:30:44 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 7/8] pci: Add CircuitCo VENDOR ID and MinnowBoard DEVICE ID |
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On 06/26/2013 12:37 PM, Bjorn Helgaas wrote: > > Yeah, that's what I was thinking. > > But Peter's comment makes more sense to me now. The spec refers to > that config register as "Subsystem ID," not "Subsystem Device ID," but > I was confused because most existing usage treats it as a device ID. > For example, the field in struct pci_device_id is named "subdevice," > and all the existing #defines in pci_ids.h are of the form > PCI_SUBDEVICE_ID_*. > > Device IDs are pretty specific identifiers, so I was thinking that a > "sub-device ID" would be even more specific. Then it would make no > sense to have a "sub-device ID" that was as generic as "MINNOWBOARD." > But the register is actually *not* a "sub-device ID," and I can see > that using the same Subsystem ID for all the devices on a board might > make sense. >
Subsystem IDs is basically a board ID in the traditional PC view, but they didn't call it that because it would have been confusing in other, nontraditional configurations.
Microsoft has a "best practices" document, which may end up becoming basis for a future PCI-SIG document clarifying the standard:
http://msdn.microsoft.com/en-us/library/windows/hardware/gg463287.aspx
-hpa
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