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Author Topic: More "traditional" /boot on *plugs?  (Read 3743 times)
Nightmonkey
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« on: June 10, 2010, 06:15:05 PM »

Howdy. I've successfully updated my kernel on my GuruPlug S+ with the with-linux.com 2.6.34 kernel. However, I'm curious if one can use a regular filesystem to store the kernel on the *plugs NAND with u-boot? If so, are there downsides to doing so? Is there some doc out there which details why the uImage method is used?

Not a big deal, but I'm curious to understand more.

Thanks! Smiley
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fragfutter
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« Reply #1 on: June 10, 2010, 11:37:45 PM »

nand is a non traditional block device. To "mount" it from within linux, it requires a special filesystem (jffs2, ubifs).

U-Boot can read directly from the nand. But it does not know about jffs2/ubifs.

Now that u-boot is the one that needs to load the kernel, you need to stick with what u-boot knows.
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sfzhi
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« Reply #2 on: June 11, 2010, 04:34:03 AM »

U-Boot can read directly from the nand. But it does not know about jffs2/ubifs.

Actually, u-boot does know about jffs2/ubifs. It can load kernel from inside jffs2 just fine. I haven't tried ubifs though.
As far as I can tell by looking at the u-boot sources, there is some code to deal with ubifs, but I don't know what exactly it can do and how complete it is.
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Nightmonkey
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« Reply #3 on: June 12, 2010, 03:08:20 PM »

Thanks for the background info. I guess that even though U-Boot has ubifs support, the plugs haven't been around long enough to really test out the ubifs code and ensure that the kernel-as-a-file (vmlinuz/bzImage/etc.) on a filesystem works. If I get a chance to do more U-Boot doc reading, I'll see if I can give it a hacker's try. Smiley
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birdman
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« Reply #4 on: June 13, 2010, 11:12:03 AM »

...the plugs haven't been around long enough to really test out the ubifs code and ensure that the kernel-as-a-file (vmlinuz/bzImage/etc.) on a filesystem works.
I' have it booting uImage from an ext2 file-system (on an SD card), so kernel-as-a-file works.   The question is whether uboot can see your file system.
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flipflip
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« Reply #5 on: June 15, 2010, 11:01:33 AM »

Actually, u-boot does know about jffs2/ubifs. It can load kernel from inside jffs2 just fine. I haven't tried ubifs though.
As far as I can tell by looking at the u-boot sources, there is some code to deal with ubifs, but I don't know what exactly it can do and how complete it is.

I've been playing with this but couldn't get it to work. This is how far I got: http://oinkzwurgl.org/guruplug_uboot
Not sure what the exact problem is. Maybe the ubifs stuff in the u-boot I used is different from what they used to initialise the NAND.
It would be nice to be able to boot from the flash partition or the SD card. One could easily update the kernel and use an initrd.
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soxs060389
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« Reply #6 on: July 06, 2010, 12:39:07 PM »

How did you achiev it to make uboot actually boot from ext2 SD card partition? Is there somehowto or some hints what to do with uboot env variables? Thanks for any advice. (I don't feel like flashing NAND to death :> )
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fragfutter
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« Reply #7 on: July 06, 2010, 12:55:33 PM »

here are the hints: mmcinit and ext2load (but only on sheevaplug)
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flipflip
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« Reply #8 on: July 06, 2010, 12:55:41 PM »

I didn't. I needed to flash the kernel, then boot it from flash. Then, once the kernel took over, it can boot the system from the SD card.
Don't worry about the flash. You can probably flash that more often than you have time to.

I'm now pretty happy with my setup. I'm not planning to upgrade the kernel anytime soon. And the plug is now my router, access point, etc. Hence, I cannot play with it anymore anyway :-)
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soxs060389
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« Reply #9 on: July 06, 2010, 01:50:47 PM »

I found pretty much to do within the next weeks, but one question is still open: Is the libertas_sdio driver going mainline anytime soon? 2.6.35-rc4 does not seem to include it.
And where can I find a howto, to adjust or find the position within files that changed between 2.6.32 and 2.6.35-rc4 AND still need to be patched?
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tylernt
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« Reply #10 on: July 06, 2010, 05:47:15 PM »

How did you achiev it to make uboot actually boot from ext2 SD card partition? Is there somehowto or some hints what to do with uboot env variables? Thanks for any advice. (I don't feel like flashing NAND to death :> )
Here's how I boot off of an SD card:

http://plugcomputer.org/plugforum/index.php?topic=1918.msg11139

I use a FAT-formatted SD card for ease of using my Windows box to update my kernel or initrd, but ext2 should work just fine by using the ext2load uBoot command that fragfutter mentions.
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birdman
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« Reply #11 on: November 03, 2010, 06:48:23 PM »

Actually, u-boot does know about jffs2/ubifs. It can load kernel from inside jffs2 just fine. I haven't tried ubifs though.
Do you know which command you would use to load a file from a jffs2 file system with u-boot?  I'd like to do this (well, I'd like to use ubifs, but anything that can load a file from a file-system on NAND would be OK).
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odoll
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« Reply #12 on: November 04, 2010, 02:10:08 AM »

wouldn't that http://plugcomputer.org/plugwiki/index.php/Enabling_UBIFS answer your question?
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birdman
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« Reply #13 on: November 04, 2010, 06:44:57 PM »

No.  That's all about creating a ubifs file-system for the root partition - i.e. one that can be read by Linux.
I'm interested in getting u-boot to read a file from a ubifs file-system on the mtd device (NAND).    So an ext2load command - but for ubifs on mtd.
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odoll
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« Reply #14 on: November 26, 2010, 09:58:09 AM »

http://www.plugcomputer.org/plugwiki/index.php/Installing_Debian_To_Flash#Convert_internal_flash_root_partition_to_UBIFS !?
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