Dear coreboot folks,
Am Sonntag, den 20.01.2013, 23:46 +0100 schrieb Paul Menzel:
> 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.
Well, reading the ACPI specification [4], 0 is only allowed, if there is
no PBlockAddress.
18.5.93 Processor (Declare Processor)
[…]
PBlockAddress provides the system I/O address for the processors
register block. Each processor can supply a different such
address. PBlockLength is the length of the processor register
block, in bytes and is either 0 (for no P_BLK) or 6. With one
exception, all processors are required to have the same
PBlockLength. The exception is that the boot processor can have
a non-zero PBlockLength when all other processors have a zero
PBlockLength. It is valid for every processor to have a
PBlockLength of 0.
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
[4] http://acpi.info/DOWNLOADS/ACPIspec40a.pdf
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