Hi,

I start a new thread, as this is now became another issue. Still working
on getting a RS232 PCIe card running in a non-root Linux cell.

The good news: basically, it works. I can send and receive data via MSI
ints.

serial 0000:17:00.0: enabling device (0400 -> 0403)
querying PCI -> IRQ mapping bus:23, slot:0, pin:0.
serial 0000:17:00.0: can't find IRQ for PCI INT A; probably buggy MP table
0000:17:00.0: ttyS2 at I/O 0x4008 (irq = 24, base_baud = 115200) is a
ST16650V2

I still see the 'buggy MP' error, but it can be ignored as the driver
will eventually use MSI.


Two bad news: Linux's 8250 driver needs patching. At least we need some
parameter like 8250.platform=disable to disable the probing for platform
uarts. Why?

ATM, we must specify 8250.nr_uarts. Otherwise the kernel will touch
restricted ports. It does touch those ports, as it lacks ACPI platform
information and assumes 'any' platform UART is present.

I.e.:
  8250.nr_uarts=1 only touches 0x3f8
  8250.nr_uarts=2 touches 0x3f8 and 0x2f8
  8250.nr_uarts=3 touches 0x3f8, 0x2f8, 0x3e9 (?)

In addition to that I have a PCI device. And Linux won't probe it until
it probed all other PIO ports. If I specify 8250.nr_uarts=1 (as I do
want to restrict access to 0x2f8), it will never probe the PCI device.

So at the moment, the hack is to set 8250.nr_uarts=4 and permit access
to all ports. Yikes. At least I now know that the PCI device basically
works, but still, this needs to be patched.


Second thing: Sending/receiving works fine, but I still get VT-d fault
events. Such like:

VT-d fault event reported by IOMMU 0:
 Source Identifier (bus:dev.func): 17:00.0
 Fault Reason: 0x22 Fault Info: 8e000000000 Type 0

... We don't have IR-PCI-MSI in non-root cells, right? So where does
this fault come from?

Note that before handing over the device to the non-root cell, the root
cell didn't load the driver for the device, so it should be handed over
unitialised.

Thanks
  Ralf

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