Someone can explain me this?

[dimitriz]

Hi

i'm trying to recompile the kernel of my kobo Glo, i prepare the environment and compiled creating uImage...

before try to flash, i removed the internal SD and made a backup with dd if=/dev/internal-sd of=backup.img bs=4M

then, i flashed the uImage
dd if=uImage of=/dev/internal-sd bs=512 seek=2048

...

when i put this into the Kobo, this not work.. ok, no problem i think... just return the image i have backuped... but it not works.. i spend all the day trying to recover the kobo and after a lot of trying (get uImage from the kobo 3.8.0 firmware package and the u-boot-mddr) and i have to erase the recovery and the rootfs partition and replace with contents of the backuped backup.img ...

alot of troubles...

someone can say me why this not works? maybe because bs=4M ?? i did something wrong??




after that, using the post to another thing... i'm needing to recompile the firmware just to change the console from ttymxc0 to tty0 (i need free ttymxc0 to use with an TTL bluetooth module), this is not working and i think its because the kernel console is running under the ttymxc0



thanks alot for any information

[Aydan]

Did you backup the whole sd-card or only the partition? (e.g. /dev/sda or /deb/sda1)
to check this you can do "fdisk -l backup.img", which should give you a list of three partitions.
If i remember correctly the console is given in the commandline which is defined in uboot so you'll have to modify the uboot default config and recompile/flash that.
You'll also have to modify /etc/inittab and remove the line starting a logon shell on ttymxc0

Regards
Aydan

[dimitriz]

the whole sd card... using /dev/sdc in my case...
i can fdisk in the image, and i can mount this with offset to mount the partitions, this is the way i get the files back to recover. i dont understand why the dd back to the sd card dont work

i removed the line in inittab but it seems to need some more modification.

thanks for reply

[Lucas Malor]

Maybe you had some bad cluster:

https://wiki.archlinux.org/index.php...tire_hard_disk

[Aydan]

Originally Posted by dimitriz

i removed the line in inittab but it seems to need some more modification.

There's three situations where messages appear on the serial:
uboot startup -> modify uboot
kernel startup -> modify cmdline config defaults of uboot or modify uboot env
linux console -> modify inittab (which you already did)

I suspect you still get kernel messages but no login prompt.

Regards
Aydan

[dimitriz]

Thanks Aydan!

I Did more or less what you said.

extract first 4mb from the card
# dd if=/dev/sdc of=first-4m.bkp bs=1024 count=4096

hex edit first-4m.bkp and replace 2 entries of ttymxc0 to another console...

reflash with
# dd if=first-4m.bkp of=/dev/sdc bs=1024

doing this, now my dmesg doest show using ttymxc0 anymore, i think i did it right...

but...


i still getting no messages from the TTL port...

i'm doing this :

# cat /dev/ttymxc0 &
# while true; do echo Message > /dev/ttymxc0 ; done

then, i'm shorting RX and TX pins..

teoricaly i think i have to receive the "Message" in console... but nothing happens... but i already did this before mess up with the kernel and sd image... and i receive the messages when shorting RX and TX, but with delay and other strange characters... this is why i think the kernel is messing up the messages and let try to remove this...

i'm thinking... there's some chance the new kernel is not working with ttymxc0? any ideas to the next step?

thanks

[dimitriz]

i replaced uImage from 3.5.0 kernel...

now i'm receiving the messages again...

# cat /dev/ttymxc0
# while true; do printf 'MESSAGE!!' > /dev/ttymxc0; done

and shorting /dev/ttymxc0 rx and tx

but here is the output, something is messing up with the messages

[dimitriz]

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