Invalid PBLK length by systemd - only few kernel versions

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1

This message is in journaldctl:
archlinux kernel: acpi ACPI0007:06: Invalid PBLK length [-1702717723]
16 times
this is exactly the number of CPU-cores (AMD Ryzen7 3700x (8 core CPU))
…
BUT only using kernels:
6.6.89-1
6.1.137-1
NOT if using kernels:
6.12.27-1
6.14.5-2
6.15.0-rc5-1
Reason may be an BIOS update;
Does someone have an idea which parameter triggers this???

2

A quick search on Google for “invalid pblk length 8” brought up a lot of results, and they seem to indicate that it is most likely a BIOS issue.

The section of code which produces the error can be found between lines 376 & 399 of the linux/drivers/acpi/acpi_processor.c GitHub file:

	/*
	 * On some boxes several processors use the same processor bus id.
	 * But they are located in different scope. For example:
	 * \_SB.SCK0.CPU0
	 * \_SB.SCK1.CPU0
	 * Rename the processor device bus id. And the new bus id will be
	 * generated as the following format:
	 * CPU+CPU ID.
	 */
	sprintf(acpi_device_bid(device), "CPU%X", pr->id);
	dev_dbg(&device->dev, "Processor [%d:%d]\n", pr->id, pr->acpi_id);

	if (!object.processor.pblk_address)
		dev_dbg(&device->dev, "No PBLK (NULL address)\n");
	else if (object.processor.pblk_length != 6)
		dev_err(&device->dev, "Invalid PBLK length [%d]\n",
			    object.processor.pblk_length);
	else {
		pr->throttling.address = object.processor.pblk_address;
		pr->throttling.duty_offset = acpi_gbl_FADT.duty_offset;
		pr->throttling.duty_width = acpi_gbl_FADT.duty_width;

		pr->pblk = object.processor.pblk_address;
	}
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3

==> Apparently this is the result of a BIOS not implementing the ACPI specification correctly.

The kernels 6.12 / 6.14 / 6.15 are not affected…
Only 6.1 / 6.6 - and only on one of two machines (both with (different) Ryzen CPU
and AMD-Graphicscard) are affected…
Some kernel regression as usual?? :innocent:
Found:
…Linux might not be able to make your processor enter low-power modes
and/or control dynamic frequency scaling properly.
Nothing to worry about, not really that much that you can do about it either.

4

i started getting it since the 14.5.25 update.
i’m on kernel 6.6
at some point i’ll move to a later Kernel.

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5

I did it: Kernels 6.12 to 6.15rc are o.K.

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