I am working on an Embedded ARM9 development board. In that i want rearrange my nand partitions. Can anybody tell me how to do that ?
In my u-boot shell if i give the command mtdparts which gives following information .
Boardcon> mtdparts
device nand0 <nandflash0>, # parts = 7
#: name size offset mask_flags
0: bios 0x00040000 0x00000000 0
1: params 0x00020000 0x00040000 0
2: toc 0x00020000 0x00060000 0
3: eboot 0x00080000 0x00080000 0
4: logo 0x00100000 0x00100000 0
5: kernel 0x00200000 0x00200000 0
6: root 0x03c00000 0x00400000 0
active partition: nand0,0 - (bios) 0x00040000 @ 0x00000000
defaults:
mtdids : nand0=nandflash0
mtdparts: mtdparts=nandflash0:256k@0(bios),128k(params),128k(toc),512k(eboot),1024k(logo),2m(kernel),-(root)
Kernel boot message shows the following :
Creating 3 MTD partitions on "NAND 64MiB 3,3V 8-bit":
0x000000000000-0x000000040000 : "Boardcon_Board_uboot"
0x000000200000-0x000000400000 : "Boardcon_Board_kernel"
0x000000400000-0x000003ff8000 : "Boardcon_Board_yaffs2"
Anybody can please explain me what is the relation between both these messages . And which one either kernel or u-boot is responsible for creating partions on nand flash?. As for as i know kernel is not creating partitions on each boot but why the message "Creating 3 MTD partitions"?
The Memory Technology Device (MTD) interface is a way of abstracting flash devices as if they were normal block devices. With the densities of these flash chips increasing, the need for partitioning is becoming more apparent. Unlike typical block devices, however, these flash devices generally lack a partition table.
The two boot hardware partitions are special and play an important role when the bootloader is started. The CPU can access their content in a simplified manner, which accelerates loading and running a bootloader. Some eMMC devices allow to configure their size as well.
NAND flash is a sequential access device appropriate for mass storage applications, while NOR flash is a random access device appropriate for code storage application. NOR Flash can be used for code storage and code execution. Code stored on NAND Flash can't be executed from there.
Flashing with U-BootUnmount, insert the microSD card in your COM and wait for u-boot to load from mmc. Interrupt the boot process when you see Hit any key to stop autoboot and enter these commands. Remove the SD card and restart your system. If all went well, your system should start normally.
For flash devices, either NAND or NOR, there is no partition table on the device itself. That is, you can't read the device in a flash reader and find some table that indicates how many partitions are on the device and where each partition begins and ends. There is only an undifferentiated sequence of blocks. This is a fundamental difference between MTD flash devices and devices such as disks or FTL devices such as MMC.
The partitioning of the flash device is therefore in the eyes of the beholder, that is, either U-Boot or the kernel, and the partitions are "created" when beholder runs. That's why you see the message Creating 3 MTD partitions
. It reflects the fact that the flash partitions really only exist in the MTD system of the running kernel, not on the flash device itself.
This leads to a situation in which U-Boot and the kernel can have different definitions of the flash partitions, which is apparently what has happened in the case of the OP.
In U-Boot, you define the flash partitions in the mtdparts
environment variable. In the Linux kernel, the flash partitions are defined in the following places:
gpmi-nfc-mil.c
or other driver source code. (what a bummer!).root=/dev/mmcblk0p2 rootwait console=ttyS2,115200 mtdparts=nand:6656k(all),1m(squash),-(jffs2)
The type of partitioning support that you have in the kernel therefore depends on the type of flash you are using, whether it's driver supports kernel command line parsing and whether your kernel has device tree support.
In any event, there is an inherent risk of conflict between the U-Boot and kernel partitioning of the flash. Therefore, my recommendation is to define the flash partitions in the U-Boot mtdparts
variable and to pass this to the kernel in the U-Boot kernel command line, assuming that your kernel support this option.
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