[PATCH] Fix and enable EDAC sysfs operation

to generate parity.  Some vendors do not do this, and thus the parity bit

can "float" giving false positives.

The PCI Parity EDAC device has the ability to "skip" known flaky

cards during the parity scan. These are set by the parity "blacklist"

interface in the sysfs for PCI Parity. (See the PCI section in the sysfs

section below.) There is also a parity "whitelist" which is used as

an explicit list of devices to scan, while the blacklist is a list

of devices to skip.

[There are patches in the kernel queue which will allow for storage of

quirks of PCI devices reporting false parity positives. The 2.6.18

kernel should have those patches included. When that becomes available,

then EDAC will be patched to utilize that information to "skip" such

devices.]

EDAC will have future error detectors that will be added or integrated

into EDAC in the following list:

EDAC will have future error detectors that will be integrated with

EDAC or added to it, in the following list:

	MCE	Machine Check Exception

	MCA	Machine Check Architecture

there currently reside 2 'edac' components:

	mc	memory controller(s) system

	pci	PCI status system

	pci	PCI control and status system

============================================================================

Memory Controller (mc) Model

First a background on the memory controller's model abstracted in EDAC.

Each mc device controls a set of DIMM memory modules. These modules are

Each 'mc' device controls a set of DIMM memory modules. These modules are

laid out in a Chip-Select Row (csrowX) and Channel table (chX). There can

be multiple csrows and two channels.

be multiple csrows and multiple channels.

Memory controllers allow for several csrows, with 8 csrows being a typical value.

Yet, the actual number of csrows depends on the electrical "loading"

of a given motherboard, memory controller and DIMM characteristics.

Dual channels allows for 128 bit data transfers to the CPU from memory.

Some newer chipsets allow for more than 2 channels, like Fully Buffered DIMMs

(FB-DIMMs). The following example will assume 2 channels:

		Channel 0	Channel 1

	The time period, in milliseconds, for polling for error information.

	Too small a value wastes resources.  Too large a value might delay

	necessary handling of errors and might loose valuable information for

	locating the error.  1000 milliseconds (once each second) is about

	right for most uses.

	locating the error.  1000 milliseconds (once each second) is the current

	default. Systems which require all the bandwidth they can get, may

	increase this.

	LOAD TIME: module/kernel parameter: poll_msec=[0|1]

	RUN TIME: echo "1000" >/sys/devices/system/edac/mc/poll_msec

Module Version read-only attribute file:

	'mc_version'

	The EDAC CORE module's version and compile date are shown here to

	indicate what EDAC is running.

============================================================================

'mcX' DIRECTORIES

DIMM capability attribute file:

	'edac_capability'

	The EDAC (Error Detection and Correction) capabilities/modes of

	the memory controller hardware.

DIMM Current Capability attribute file:

	'edac_current_capability'

	The EDAC capabilities available with the hardware

	configuration.  This may not be the same as "EDAC capability"

	if the correct memory is not used.  If a memory controller is

	capable of EDAC, but DIMMs without check bits are in use, then

	Parity, SECDED, S4ECD4ED capabilities will not be available

	even though the memory controller might be capable of those

	modes with the proper memory loaded.

Memory Type supported on this controller attribute file:

	'supported_mem_type'

	This attribute file displays the memory type, usually

	buffered and unbuffered DIMMs.

Memory Controller name attribute file:

	'mc_name'

	that is being utilized.

Memory Controller Module name attribute file:

	'module_name'

	This attribute file displays the memory controller module name,

	version and date built.  The name of the memory controller

	hardware - some drivers work with multiple controllers and

	this field shows which hardware is present.

Total memory managed by this memory controller attribute file:

	'size_mb'

	This attribute file will display what type of memory is currently

	on this csrow. Normally, either buffered or unbuffered memory.

	Examples:

		Registered-DDR

		Unbuffered-DDR

EDAC Mode of operation attribute file:

	'dev_type'

	This attribute file will display what type of DIMM device is

	being utilized. Example:  x4

	This attribute file will display what type of DRAM device is

	being utilized on this DIMM.

	Examples:

		x1

		x2

		x4

		x8

Channel 0 CE Count attribute file:

If logging for UEs and CEs are enabled then system logs will have

error notices indicating errors that have been detected:

MC0: CE page 0x283, offset 0xce0, grain 8, syndrome 0x6ec3, row 0,

EDAC MC0: CE page 0x283, offset 0xce0, grain 8, syndrome 0x6ec3, row 0,

channel 1 "DIMM_B1": amd76x_edac

MC0: CE page 0x1e5, offset 0xfb0, grain 8, syndrome 0xb741, row 0,

EDAC MC0: CE page 0x1e5, offset 0xfb0, grain 8, syndrome 0xb741, row 0,

channel 1 "DIMM_B1": amd76x_edac

PCI Device Whitelist:

	'pci_parity_whitelist'

	This control file allows for an explicit list of PCI devices to be

	scanned for parity errors. Only devices found on this list will

	be examined.  The list is a line of hexadecimal VENDOR and DEVICE

	ID tuples:

	1022:7450,1434:16a6

	One or more can be inserted, separated by a comma.

	To write the above list doing the following as one command line:

	echo "1022:7450,1434:16a6"

		> /sys/devices/system/edac/pci/pci_parity_whitelist

	To display what the whitelist is, simply 'cat' the same file.

PCI Device Blacklist:

	'pci_parity_blacklist'

	This control file allows for a list of PCI devices to be

	skipped for scanning.

	The list is a line of hexadecimal VENDOR and DEVICE ID tuples:

	1022:7450,1434:16a6

	One or more can be inserted, separated by a comma.

	To write the above list doing the following as one command line:

	echo "1022:7450,1434:16a6"

		> /sys/devices/system/edac/pci/pci_parity_blacklist

	To display what the whitelist currently contains,

	simply 'cat' the same file.

=======================================================================

PCI Vendor and Devices IDs can be obtained with the lspci command. Using

the -n option lspci will display the vendor and device IDs. The system

administrator will have to determine which devices should be scanned or

skipped.

The two lists (white and black) are prioritized. blacklist is the lower

priority and will NOT be utilized when a whitelist has been set.

Turn OFF a whitelist by an empty echo command:

	echo > /sys/devices/system/edac/pci/pci_parity_whitelist

and any previous blacklist will be utilized.