[coreboot] ASRock E350M1/AMD Persimmon: Linux 3.2.x complains about `ACPI: Invalid PBLK length [0]`

Paul Menzel paulepanter at users.sourceforge.net
Sun Jan 20 23:46:17 CET 2013


Dear coreboot folks,


Am Sonntag, den 20.01.2013, 11:50 +0100 schrieb Paul Menzel:

> in Debian Sid/unstable with Linux 3.2.35 looking at the Linux messages
> in the output of `dmesg` I see
> 
>         ACPI: Invalid PBLK length [0]
> 
> which results from
> 
>         $ more src/mainboard/asrock/e350m1/dsdt.asl
>         […]
>         	/*
>         	 * Processor Object
>         	 *
>         	 */
>         	Scope (\_PR) {		/* define processor scope */
>         		Processor(
>         			C000,		/* name space name, align with BLDCFG_PROCESSOR_SCOPE_NAME[01] */
>         			0,		/* Unique number for this processor */
>         			0x810,		/* PBLK system I/O address !hardcoded! */
>         			0x06		/* PBLKLEN for boot processor */
>         			) {
>         		}
>         
>         		Processor(
>         			C001,		/* name space name */
>         			1,		/* Unique number for this processor */
>         			0x810,		/* PBLK system I/O address !hardcoded! */
>         			0x00		/* PBLKLEN for boot processor */
>         			) {
>         		}
>         		Processor(
>         			C002,		/* name space name */
>         			2,		/* Unique number for this processor */
>         			0x810,		/* PBLK system I/O address !hardcoded! */
>         			0x00		/* PBLKLEN for boot processor */
>         			) {
>         		}
>         		Processor(
>         			C003,		/* name space name */
>         			3,		/* Unique number for this processor */
>         			0x810,		/* PBLK system I/O address !hardcoded! */
>         			0x00		/* PBLKLEN for boot processor */
>         			) {
>         		}
>         	} /* End _PR scope */
>         […]
> 
> Is that an error in the Linux ACPI code? According to Colin King’s
> comment (25) to the Launchpad report [1], the ACPI specification allows
> it to be set to 0.
> 
>         »Section 18.5.93 of the ACPI specification states that the
>         PBlockLength is the length of the processor register block, in
>         bytes and is either 0 (for no P_BLK) or 6.« [2]
> 
> So the DSDT seems to be valid. Before I report that to the Linux ACPI
> folks, could you please tell me if I am missing something?

Looking at the Linux code in `drivers/acpi/processor_driver.c` only 6
seems to be allowed [2].

        static int acpi_processor_get_info(struct acpi_device *device)
        {
        […]
        	/*
        	 * 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);
        	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Processor [%d:%d]\n", pr->id,
        			  pr->acpi_id));
        
        	if (!object.processor.pblk_address)
        		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No PBLK (NULL address)\n"));
        	else if (object.processor.pblk_length != 6)
        		printk(KERN_ERR PREFIX "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;
        
        		/*
        		 * We don't care about error returns - we just try to mark
        		 * these reserved so that nobody else is confused into thinking
        		 * that this region might be unused..
        		 *
        		 * (In particular, allocating the IO range for Cardbus)
        		 */
        		request_region(pr->throttling.address, 6, "ACPI CPU throttle");
        	}
        […]
        }

So I am going to submit a bug report to the Linux ACPI folks tomorrow.


Thanks,

Paul


> [1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/197267
> [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/197267/comments/25
[3] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/acpi/processor_driver.c;h=e83311bf1ebdaaaea1adbf2de1351cca907d3465;hb=5da1f88b8b727dc3a66c52d4513e871be6d43d19#l351
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