I find out my mistakes... I have broken bootmenu files in /home/user/MyDocs (bootmenu.scr and bootmenu.img.d/) and images there no longer match expected power kernel version installed on my latest rootfs/optfs backup !

Thanks to BackupMenu USB mass storage mount, I fixed content of /home/user/MyDocs and get my boot menu back and my full system. If I had guessed the mistake I did first, I would not have restored that backup as rootfs and optfs were not concerned by the defect.

WARNING!
Do (or try to do) it on your own responsibility.
I do not take any responsibility for broken/bricked/forced-to-reflashing devices.

I was able to run BackupMenu (v. 1.1) on the U-boot.
How?
1. I downloaded backupmenu-uboot.zip. This file have been uploaded few times on BackupMenu's thread.
2. I unpacked all files on root directory of my sdcard. If you have more than one partition - the first one must be FAT.
3. I turned off my N900 and turned on.
4. When showed U-Boot I have interrupted the counter and went to U-boot console
5. I typed "run sdboot"
6. After some time it booted BackupMenu.
There were some errors and GUI was slightly broken but I was able to make a backup on eMMC, restore it and boot the Maemo so at least backup & restore seem to work.
I didn't checked other functions because I don't use them.

All the thanks for the author of backupmenu-uboot.zip file.
I didn't make anything unusual.

EDIT:
Important note!
Try to avoid the "Quit and reboot" function in BackupMenu when you run it using my way. Using it may cause some lags when you booted Maemo after using that function.

Hello.
I've got a little problem. I renamed the default "bootmenu.img.d" to ".bootmenu.img.d", cause I hate seeing this directory any time I use FileBox (yes, I know, pretty silly decision). Now my phone doesn't want to boot any kernel, even the default one. Any way to rename that directory back so I can use my phone without reflashing? I tried connecting my phone via usb hoping that it will be detected as usb-storage so I can rename the folder, but Windows doesn't want to recognize it.
Any way to solve the problem using U-Boot console, or, whatever? Thanks in advance.

You should be able to boot attached kernel (stock nokia one) which is stored in nand together with uboot.

Other option is to prepare kernel in uImage format and store it on SD card (name uImage). And via uboot console boot it via "run sdboot" command.

> You should be able to boot attached kernel (stock nokia one) which is stored in nand together with uboot.
But I can't. The phone simply reboots after chosing the default osso-kernel.

Any command to chose the image to boot from console?

Look at available RX-51 commands in README file:
http://git.denx.de/?p=u-boot.git;a=b...nokia_rx51#l45

and their defintions in uboot source code:
http://git.denx.de/?p=u-boot.git;a=b...ia_rx51.h#l281

Basically, to load & book kernel from mmc device (eMMC or SD) card you need:
1) specify mmc device
2) specify mmc partition number
3) specify mmc partition type
4) load kernel file to memory address
5) boot image from memory address

For that set variables mmcnum, mmcpart, mmctype and mmckernfile. And then run trymmckernboot.

===

Another option is to connect phone via usb to computer via flasher-3.5 or 0xFFFF load kernel image (in load, not flash) mode and then boot it. This will allows you to boot temporary kernel without flashing it to nand...

Hello guys. I have a small question.
I have the last u-boot form pali 2013.04.
I reformatted my MyDocs to ext3.
no i get "Unrecognised filesystem type"

I still can boot the attached kernel (NAND), but no other kernels.

Where i can set the filesystem type ext3? for the u-boot?

Thanks

Have you run "u-boot-update-bootmenu" after reformatting MyDocs?
are the u-boot kernels still in place? (i.e. after reformatting).

Run u-boot-update-menu and post the output here. It might help for diagnosing.

Yes of course i run it.
u-boot-update-menu find all Menu items and kernels. It also said that the default Menu item is kernel-power53 as i set it.
After i boot the mobile all menu items are correctly displayed but when i choose one it say "Unrecognised filesystem type"
:-(

I remember some problems with MyDocs formatted in fat from gparted or other tools. But iirc pali enabled all 'default' file formats.
How did you format it?