On 2021/7/16 22:25, Bjorn Helgaas wrote:
On Fri, Jul 16, 2021 at 10:04:51PM +0800, Wenchao Hao wrote:
On 2021/7/15 1:26, Keith Busch wrote:
On Wed, Jul 14, 2021 at 11:54:27AM -0500, Bjorn Helgaas wrote:
On Wed, Jul 14, 2021 at 02:33:37PM +0800, Wenchao Hao wrote:
If they are not fixed, then is there anyway I can get a fixed ID
which can indicate physical connection.
You can look at the "lspci -P" option. I'm not really familiar with
this, but I think Matthew (cc'd) implemented it.
That option shows the parent devices for each listed device, but that
may not produce the same output if BDf doesn't always enumerate the
same.
I think Wenchao was seeking some invariant device identification that
can be used to look up its BDf. There's no PCI level requirement for
uniquely identifying a specific device across changing topologies, so I
don't think this is generically possible.
Yes, I want a way to access device which can keep unchanged, a
direction is according to hardware. If we have anyway which makes
it possible for software can describe hardware connection would
satisfy our demand.
I don't know whether this would be useful, but PCI does define an
optional "Device Serial Number" extended capability. It has issues
like the fact that many devices don't support it at all, and even on
devices that do support it, the serial number may not actually be
unique. There is minimal support for this in Linux (pci_get_dsn()),
but it is currently not exposed to userspace via sysfs.
Bjorn
.
This "Device Serial Number" seems can not satisfy our demand because it
is looks
not a general ID. According to BIOS conclusion, if we can the hardware keeps
unchanged, the BUS number would not change. We would put some
restrictions as
workaround temporarily.
Thanks a lot for your suggestions.
