How to Find NAND Parameters
Table of Contents
Using the Datasheet
If you are writing a driver or do not have a working Linux kernel for the board, then you should use the datasheet to find the parameters for your NAND flash. This section describes where to find the relevant information for building JFFS2 or UBI images using the datasheet for your device.
Flash Vendor
The flash vendor is typically on the chip, although it can be difficult to discern at times.
- Samsung - "SAMSUNG" written on the chip itself.
- Micron - "M" with an oval surrounding it
- ST Micro - "ST" logo (Black letters, white background)
- Numonyx - Stylized "N"
Flash Model
Like the vendor, it is easiest to look at the board's BOM. It is also typically on the chip, although it may include additional numbers and letters that indicate a particular subset of the model, making it somewhat difficult to find the datasheet.
Size or Density
The datasheet for the given part is the best place to find the size of the NAND flash chip. It is typically called the chip's density, and will be expressed in either MibiBytes (1*2^20 bytes), or even as MBits (MiB * 8). We are unaware of any manufacturer that expresses them in powers of 10 (like hard drive manufacturers).
Some datasheets may correspond to multiple densities of the same family of devices. In those cases, there is typically a section of the datasheet that will explain how to read the model number to determine the density of the chip.
The density, as well as other size parameters, are typically expressed in terms of the size of the data and the out-of-band (OOB) region that accompany each page. The OOB size can be ignored when passing parameters to JFFS2 or UBI.
Physical Erase Block Size
The physical erase block size (or PEB) is the size of each erasable block of NAND. This value can be found in the datasheet under the feature summary section. It will be expressed in bytes or words.
Logical Erase Block Size
The logical erase block size (LEB) is an UBIFS-only term, and is not entirely straightforward to figure out. UBIFS prepends a header to every block of a certain size, and aligns it with the page. It is related to physical eraseblock size, minimum input/output unit size, and sub-page size. The easiest way to find it is to attach the device to UBI and see the output, as described below.
Some typical values:
- NAND flash with 512 byte NAND page and 256 byte sub-page: LEB size is PEB size minus 512;
- NAND flash with 2048 byte NAND page and 512 byte sub-page: LEB size is PEB size minus 2048;
- NAND flash with 2048 byte NAND page and no sub-page: LEB size is PEB size minus 4096.
See: http://www.linux-mtd.infradead.org/faq/ubifs.html#L_find_lebsz
Page Size or Minimum I/O Size
Each device is divided into some number of pages. The page is the minimum block of data that can be read or programmed at a time. This corresponds to the minimum I/O size of the UBI subsystem.
This information can be found in the device's datasheet as well. It will generally be found in the feature summary section at the beginning of the document, and will typically be called "Page Size". It is expressed in either Bytes or Words, depending on the bus width. Both JFFS2 and UBI want this value in terms of bytes.
This value is typically 512 bytes for low density chips (~64 MB), 2048 bytes for medium density, and 4096 bytes for very high density chips. You should always consult the datasheet for the exact value.
Sometimes sub paging is available on the flash hardware, but the driver software doesn't support subpaging. The error "bad VID header offset 512, expected 2048" is thrown when the driver can not find the VID header on boot: Subpaging can be disabled by setting subpage size equal to page size. Then the VID and EC headers will each be allocated their own page for each erase block.
Sub-page Size or Number of Partial Program Cycles
Sub-page size is a purely UBI construct, but it is related to a physical aspect of the device.
From linux-mtd:
Sub-page size is relevant only for some NAND flashes which allow several (usually 2 or 4) writes to the same NAND page. For example, many SLC NAND flashes have this. UBI utilizes this feature if it is available to waste less flash space. Typically, sub-page size is 256 in case of 512 bytes NAND page and 512 in case of 2048 bytes NAND pages. MLC NAND flashes typically have no sub-pages. SLC OneNAND chips with 2048 bytes NAND page size support 512 byte sub-pages.
Sub-page size can be derived by dividing Page Size by Number of Partial Program Cycles, or Nop. However, the sub-page support in the mtd subsystem isn't well tested, and it's much safer to use ubiattach or dmesg to find the value. See the section Using UBI below.
NOTE: Some Samsung datasheets give two values for Nop, one for the main array and one for the spare. Use the value for the Main array. The spare array refers to the OOB area, which is not used by JFFS2 or UBI.
Bus Width
Bus width describes the number of data lines used to connect the flash chip to the NAND controller, which is usually part of the SOC.
The chip's bus width can be found in the datasheet. Like density, a single datasheet may be used for chips of varying bus-widths, so you may need to find the section that describes how to decode the model number in order to determine the value. It is going to be either 8 or 16 bits.
You can also tell the bus width by looking at the schematic, although this is prone to error.
Using UBI
When a device is attached to UBI, the kernel will print a summary of the parameters of the chip. It can be found using either dmesg or ubiattach.
NOTE: You should use ubiformat to format the partition before doing this.
# ubiattach /dev/ubi_ctrl -m 0
UBI: attaching mtd0 to ubi1
UBI: physical eraseblock size: 131072 bytes (128 KiB)
UBI: logical eraseblock size: 129024 bytes
UBI: smallest flash I/O unit: 2048
UBI: sub-page size: 512
UBI: VID header offset: 512 (aligned 512)
UBI: data offset: 2048
UBI error: ubi_read_volume_table: the layout volume was not found
ubiattach: error!: cannot attach mtd0
error 22 (Invalid argument)
The -m flag refers to the mtd partition, so the above example is the geometry of /dev/mtd0.
Using the Kernel
The kernel messages will provide some information about the NAND device. You can execute the dmesg command to see the results of the NAND driver's initialization:
NAND device: Manufacturer ID: 0xec, Chip ID: 0xda (Samsung NAND 256MiB 3,3V 8-bit) AT91 NAND: 8-bit, Software ECC Scanning device for bad blocks Bad eraseblock 1020 at 0x07f80000 Bad eraseblock 1280 at 0x0a000000 Creating 2 MTD partitions on "atmel_nand": 0x00000000-0x00040000 : "Partition 1" 0x00040000-0x10000000 : "Partition 2"
Based on this, you can determine the partition scheme of the device, bad eraseblocks, bus width, and vendor.
The proc subsystem in the Linux kernel will give you some information about the NAND flash, but typically not enough to get everything up and running.
The file /proc/mtd contains the basic information about all MTDs on your board:
# cat /proc/mtd dev: size erasesize name mtd0: 00040000 00020000 "Partition 1" mtd1: 0ffc0000 00020000 "Partition 2"
Size corresponds to the density (in bytes), and erasesize corresponds to the Physical Erase Block size (in Bytes).
Common NAND Parameters
| Board | Flash Vendor | Flash Model | Size | Physical Erase Block Size | Logical Erase Block Size 1 | Page Size (Min I/O Size) | Sub-page size 1 | Bus width (Bits) | Datasheet | Notes |
|---|---|---|---|---|---|---|---|---|---|---|
| AM3517 EVM | Micron | MT29F4G16ABCHC | 512 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 16 | MT29F4G16ABCHC | - |
| AMCC 440EPx | Samsung | K9F5608U0B-PCB0 | 32 MiB | 16384 Bytes (16 KiB) | 15872 Bytes | 512 Bytes | 256 Bytes | 8 | K9F5608U0B.pdf | - |
| at91sam9260-ek | Samsung | K9F2G08U0M-PCB0 | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| at91sam9261-ek (Rev C) | Micron | MT29F2G16AABWP | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 16 | MT29F2G08AABWP | This part is obsolete |
| at91sam9261-ek (Rev D) | Samsung | K9F2G08U0A-PCB0 | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| at91sam9263-ek | Micron | MT29F2G08AAC | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | MT29F2G08AACWP | - |
| at91sam9rl-ek | Micron | MT29F2G08AAC | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | MT29F2G08AACWP | - |
| at91cap9a-dk | Micron | MT29F2G08AAC | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | MT29F2G08AACWP | - |
| at91sam9g10-ek | Micron | MT29F2G08AAC | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | MT29F2G08AACWP | - |
| at91sam9g20-ek | Samsung | K9F2G08U0A-PCB0 | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| at91sam9g45-ek | Micron | MT29F2G08AAC | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | MT29F2G08AACWP | - |
| ConnectCore Wi-MX51 | Samsung | K9F4G08U0B-PIB0 | 512 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| DVEVM6446 | Samsung | K9F1208FR0B | 64 MiB | 16384 Bytes (16 KiB) | 15360 Bytes | 512 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| i.MX27 LiteKit | ST MICRO / Numonyx | NAND512W3A2BN6E | 64 MiB | 16384 Bytes (16 KiB) | 15360 Bytes | 512 Bytes | 512 Bytes | 8 | NAND512W3A2BN6E | - |
| i.MX31 LiteKit | ST MICRO / Numonyx | NAND512W3A2CN6E | 64 MiB | 16384 Bytes (16 KiB) | 15360 Bytes | 512 Bytes | 512 Bytes | 8 | NAND512W3A2CN6E | - |
| i.MX25 PDK | Samsung | K9LAG08U0M-PCB0 | 2 GiB | 262144 Bytes (256 KiB) | 258048 Bytes | 2048 Bytes | 2048 Bytes | 8 | Contact Vendor | - |
| i.MX27 ADS | Samsung | K9K1G08U0B-J1B0 | 128 MiB | 16384 Bytes (16 KiB) | 15360 Bytes | 512 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| i.MX31 ADS | Samsung | K9K1G08U0B-J1B0 | 128 MiB | 16384 Bytes (16 KiB) | 15360 Bytes | 512 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| i.MX31 PDK | Samsung | K9F2G08R0A-JIB0 | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| KIXRP435 | Samsung | K9F1208U0B-PCB0 | 64 MiB | 16384 Bytes (16 KiB) | 15872 Bytes | 512 Bytes | 256 Bytes | 8 | Contact Vendor | - |
| MPC5121ADS | HYNIX | HY27US08121A-TPCB | 2 x 512 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 512 Bytes | 512 Bytes | 8 | HY27US08121A-TPCB | - |
| MPC8313E-RDB | Samsung | K9F5608U0D-PCB0 | 32 MiB | 16384 Bytes (16 KiB) | 15360 Bytes | 512 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| MPC8572DS | Samsung | K9F5608U0D-PCB0 | 4 x 1024 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 512 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| MPC8313E-RDB | Samsung | K9F5608U0D-PCB0 | 32 MiB | 16384 Bytes (16 KiB) | 15360 Bytes | 512 Bytes | 512 Bytes | 8 | Contact Vendor | - |
| OMAP 3530 Zoom | Micron | MT29C2G24MAKLAJG-6 IT | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 16 | MT29C2G24MAKLAJG-6 IT | - |
| OMAP 3530 Torpedo | Hynix | H8KCS0SJ0AER-46M | 256 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 16 | Contact Vendor | - |
| OMAPL138 EVM | Micron | MT29F4G08AACWC | 512 MiB | 131072 Bytes (128 KiB) | 129024 Bytes | 2048 Bytes | 512 Bytes | 8 | MT29F4G08AACWC | - |
| P1020-RDB | Samsung | K9F5608U0B-PCB0 | 32 MiB | 16384 Bytes (16 KiB) | 15872 Bytes | 512 Bytes | 256 Bytes | 8 | K9F5608U0B.pdf | - |
| Numonyx | NAND128W3A2BN6E | 16 MiB | 16384 Bytes (16 KiB) | 15360 Bytes | 512 Bytes | 512 Bytes | 8 | NAND128W3A2BN6E | - |
1 This value corresponds to using Software ECC on these chips. It will be different when using Hardware ECC.
