2009-01-28 07:33:12     Read/Write to flash from Bluetechnix CM-BF537E

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2009-01-28 07:33:12     Read/Write to flash from Bluetechnix CM-BF537E

Nikolaj Fogh (UNITED KINGDOM)

Message: 68469   

 

Hi,

 

I am using a Bluetechnix CM-BF537E board with 1.5R3 distribution and Xenomai for a data logging program.

 

Right now, I am using u-boot to execute the compiled uImage which contains the ext2 filesystem with my program in it.

 

However, I need to save some settings. I can't write it to a file, as the ext2 filesystem is loaded into volatile RAM. I don't need to save many settings, so I guess that it would be sufficient to be able to read and write to the last block of the flash chip. I have been fiddling around with some mtd drivers, but cannot seem to get it working. Is there any easy way of doing this?

 

Cheers,

 

Nikolaj Fogh

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2009-01-28 07:56:10     Re: Read/Write to flash from Bluetechnix CM-BF537E

Michael Hennerich (GERMANY)

Message: 68473   

 

I wound't use an ext2 rootfs.

 

Please use the initramfs for your volatile rootfs (less overhead and smaller)

 

Then use a small jffs2 filesystem for your files that need to be preserved during power cycle.

 

Check this:

 

http://docs.blackfin.uclinux.org/doku.php?id=linux-kernel:mtd&s[]=jffs

 

http://docs.blackfin.uclinux.org/doku.php?id=linux-kernel:jffs

 

For the CM-BF537 Core module you need GPIO-assisted Flash Chip Support !!!

 

[*] Support non-linear mappings of flash chips

<M> CFI Flash device in physical memory map

(0x20000000) Physical start address of flash mapping

(0x0) Physical length of flash mapping

(2)   Bank width in octets

<*> GPIO-assisted Flash Chip Support

 

-Michael

 

 

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2009-01-28 08:50:42     Re: Read/Write to flash from Bluetechnix CM-BF537E

Nikolaj Fogh (UNITED KINGDOM)

Message: 68479   

 

Unfortunately, the 1.5R3 distribution does not contain the GPIO assisted Flash Chip support. And trunk does not contain xenomai, which I need. I will try to backport the GPIO-assisted flash chip support to the 1.5R3 kernel and see what I can do.

 

About the ext2 rootfs. I thought that the uImage contained an ext2 filesystem, which is then loaded into a ramdisk and mapped into a /dev/mtdblock device. Is this not right? I am a bit confused about the whole mtd layer.

 

What I thought about was not to create a filesystem for the settings, but just use the raw block in the flash. There must be some easy way of doing this.

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2009-01-28 14:12:55     Re: Read/Write to flash from Bluetechnix CM-BF537E

Mike Frysinger (UNITED STATES)

Message: 68488   

 

backporting the flash driver is pretty trivial and a few people have done it ... just search the forums

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