edac.rst: move concepts dictionary from edac.h

Instead of storing the concepts dictionary inside header file,
move it to the subsystem documentation.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Mauro Carvalho Chehab 2016-10-29 16:13:23 -02:00
parent e002075819
commit 6b1fb6f703
2 changed files with 106 additions and 108 deletions

View file

@ -330,114 +330,6 @@ enum scrub_type {
#define OP_RUNNING_POLL_INTR 0x203
#define OP_OFFLINE 0x300
/*
* Concepts used at the EDAC subsystem
*
* There are several things to be aware of that aren't at all obvious:
*
* SOCKETS, SOCKET SETS, BANKS, ROWS, CHIP-SELECT ROWS, CHANNELS, etc..
*
* These are some of the many terms that are thrown about that don't always
* mean what people think they mean (Inconceivable!). In the interest of
* creating a common ground for discussion, terms and their definitions
* will be established.
*
* Memory devices: The individual DRAM chips on a memory stick. These
* devices commonly output 4 and 8 bits each (x4, x8).
* Grouping several of these in parallel provides the
* number of bits that the memory controller expects:
* typically 72 bits, in order to provide 64 bits +
* 8 bits of ECC data.
*
* Memory Stick: A printed circuit board that aggregates multiple
* memory devices in parallel. In general, this is the
* Field Replaceable Unit (FRU) which gets replaced, in
* the case of excessive errors. Most often it is also
* called DIMM (Dual Inline Memory Module).
*
* Memory Socket: A physical connector on the motherboard that accepts
* a single memory stick. Also called as "slot" on several
* datasheets.
*
* Channel: A memory controller channel, responsible to communicate
* with a group of DIMMs. Each channel has its own
* independent control (command) and data bus, and can
* be used independently or grouped with other channels.
*
* Branch: It is typically the highest hierarchy on a
* Fully-Buffered DIMM memory controller.
* Typically, it contains two channels.
* Two channels at the same branch can be used in single
* mode or in lockstep mode.
* When lockstep is enabled, the cacheline is doubled,
* but it generally brings some performance penalty.
* Also, it is generally not possible to point to just one
* memory stick when an error occurs, as the error
* correction code is calculated using two DIMMs instead
* of one. Due to that, it is capable of correcting more
* errors than on single mode.
*
* Single-channel: The data accessed by the memory controller is contained
* into one dimm only. E. g. if the data is 64 bits-wide,
* the data flows to the CPU using one 64 bits parallel
* access.
* Typically used with SDR, DDR, DDR2 and DDR3 memories.
* FB-DIMM and RAMBUS use a different concept for channel,
* so this concept doesn't apply there.
*
* Double-channel: The data size accessed by the memory controller is
* interlaced into two dimms, accessed at the same time.
* E. g. if the DIMM is 64 bits-wide (72 bits with ECC),
* the data flows to the CPU using a 128 bits parallel
* access.
*
* Chip-select row: This is the name of the DRAM signal used to select the
* DRAM ranks to be accessed. Common chip-select rows for
* single channel are 64 bits, for dual channel 128 bits.
* It may not be visible by the memory controller, as some
* DIMM types have a memory buffer that can hide direct
* access to it from the Memory Controller.
*
* Single-Ranked stick: A Single-ranked stick has 1 chip-select row of memory.
* Motherboards commonly drive two chip-select pins to
* a memory stick. A single-ranked stick, will occupy
* only one of those rows. The other will be unused.
*
* Double-Ranked stick: A double-ranked stick has two chip-select rows which
* access different sets of memory devices. The two
* rows cannot be accessed concurrently.
*
* Double-sided stick: DEPRECATED TERM, see Double-Ranked stick.
* A double-sided stick has two chip-select rows which
* access different sets of memory devices. The two
* rows cannot be accessed concurrently. "Double-sided"
* is irrespective of the memory devices being mounted
* on both sides of the memory stick.
*
* Socket set: All of the memory sticks that are required for
* a single memory access or all of the memory sticks
* spanned by a chip-select row. A single socket set
* has two chip-select rows and if double-sided sticks
* are used these will occupy those chip-select rows.
*
* Bank: This term is avoided because it is unclear when
* needing to distinguish between chip-select rows and
* socket sets.
*
* Controller pages:
*
* Physical pages:
*
* Virtual pages:
*
*
* STRUCTURE ORGANIZATION AND CHOICES
*
*
*
* PS - I enjoyed writing all that about as much as you enjoyed reading it.
*/
/**
* enum edac_mc_layer - memory controller hierarchy layer
*