[ofa-general] ib_mthca "Missing DCS"

[Roland Dreier]

 > When we moved a Meallanox HCA from one bus to another on a P5 system
 > we get the "Missing DCS" error and ib_mthca fails during init. Why
 > do we get this error and what does it mean?

It comes from this code:

	/*
	 * Check for BARs.  We expect 0: 1MB, 2: 8MB, 4: DDR (may not
	 * be present)
	 */
	if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM) ||
	    pci_resource_len(pdev, 0) != 1 << 20) {
		dev_err(&pdev->dev, "Missing DCS, aborting.\n");
		err = -ENODEV;
		goto err_disable_pdev;
	}

In other words the driver doesn't see the first mmio BAR of the PCI
device.  What does lspci show for the HCA in this case?

(Also are you moving the device while the system is running, or are
you moving the HCA when the system is down?  Hotplug "should work" but
I don't know if anyone else has tried it)

 - R.