On Tue, 15 Jul 2025 08:59:42 -0700
Matthew Wood <thepacketgeek@xxxxxxxxx> wrote:
> On Tue, Jul 15, 2025 at 4:19 AM Jonathan Cameron
> <Jonathan.Cameron@xxxxxxxxxx> wrote:
> >
> > On Sat, 12 Jul 2025 18:17:12 -0700
> > Matthew Wood <thepacketgeek@xxxxxxxxx> wrote:
> >
> > > Add a single sysfs read-only interface for reading PCIe device serial
> > > numbers from userspace in a programmatic way. This device attribute
> > > uses the same 2-byte dashed formatting as lspci serial number capability
> > > output:
> > >
> > > more /sys/devices/pci0000:c0/0000:c0:01.1/0000:c1:00.0/0000:c2:1f.0/0000:cc:00.0/device_serial_number
> > > 00-80-ee-00-00-00-41-80
> > >
> >
> > What is the use case for this? I can think of some possibilities but good to
> > see why you care here.
>
> Two primary use cases we have are for inventory tooling and health
> check tooling; being able to
> reliably collect device serial numbers for tracking unique devices
> whose BDFs could change is
> critical. Sometimes in the process of hardware troubleshooting, cards
> are swapped and BDF idents
> change but we want to track devices by serial number without possibly
> fragile regexps.
Ok. So you want to avoid having pull this from lspci output which
makes sense to me. Not sure what Bjorn and others think about this
though.
>
> >
> >
> > > Accompanying lspci output:
> > >
> > > sudo lspci -vvv -s cc:00.0
> > > cc:00.0 Serial Attached SCSI controller: Broadcom / LSI PCIe Switch management endpoint (rev b0)
> > > Subsystem: Broadcom / LSI Device 0144
> > > ...
> > > Capabilities: [100 v1] Device Serial Number 00-80-ee-00-00-00-41-80
> > > ...
> > >
> > > If a device doesn't support the serial number capability, userspace will receive
> > > an empty read:
> >
> > Better if possible to not expose the sysfs attribute if no such capability.
> > We already have pcie_dev_attrs_are_visible() so easy to extend that.
>
> That's a great point, it looks like I could match on the attribute
> name to specifically hide device_serial_number
> if the device does not support the cap, but I can't find any precedent
> for matching on a->name in pci-sysfs.c.
> Would something like this be alright after the check for pci_is_pcie(dev):
>
> if (a->name == "device_serial_number") {
> // check if device has serial, if not return 0
> }
if (a == &dev_attr_device_serial_number.attr)
or something like that.
No need for string matching.
Jonathan
>
> >
> >
> > >
> > > more /sys/devices/pci0000:00/0000:00:07.1/device_serial_number
> > > echo $?
> > > 0
> > >
> > >
> > > Matthew Wood (1):
> > > PCI/sysfs: Expose PCIe device serial number
> > >
> > > drivers/pci/pci-sysfs.c | 17 +++++++++++++++++
> > > 1 file changed, 17 insertions(+)
> > >
> >
