在 2022/9/27 AM1:18, Bjorn Helgaas 写道:

On Mon, Sep 26, 2022 at 09:31:34PM +0800, Shuai Xue wrote:

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在 2022/9/23 PM11:54, Jonathan Cameron 写道:

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I found a similar definition in arch/ia64/pci/pci.c .

	#define PCI_SAL_ADDRESS(seg, bus, devfn, reg)		\
	(((u64) seg << 24) | (bus << 16) | (devfn << 8) | (reg))

Should we move it into a common header first?

Maybe. The bus, devfn, reg part is standard bdf, but I don't think
the PCI 6.0 spec defined a version with the seg in the upper bits.
I'm not sure if we want to adopt that in LInux.

I found lots of code use seg,bus,devfn,reg with format "%04x:%02x:%02x.%x",
I am not quite familiar with PCIe spec. What do you think about it, Bjorn?

The PCIe spec defines an address encoding for bus/device/function/reg
for the purposes of ECAM (PCIe r6.0, sec 7.2.2), but as far as I know,
it doesn't define anything similar that includes the segment.  The
segment is really outside the scope of PCIe because each segment is a
completely separate PCIe hierarchy.

Thank you for your explanation.

So I probably wouldn't make this a generic definition.  But if/when
you print things like this out, please do use the format spec you
mentioned above so it matches the style used elsewhere.

Agree. The print format of bus/device/function/reg is "%04x:%02x:%02x.%x",
so I named the PMU as the same format. Then the usage flow would be:

- lspci to get the device root port in format seg/bus/device/function/reg.
	10:00.0 PCI bridge: Device 1ded:8000 (rev 01)
- select its PMU name pcie_bdf_100000.
- monitor with perf:
	perf stat -a -e pcie_bdf_200/Rx_PCIe_TLP_Data_Payload/

Bjorn and Jonathan, are you happy with this flow?

Thank you.

Best Regards,
Shuai

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