N900: JTAG or serial console over USB?
 

Does the N900 provide a JTAG or a serial console over USB?
It'd be very helpful for fixing stuff if one screws-up with partitioning the mtd device or uploading the ubifs.
I would like to avoid pulling to pieces my N900 once it finally arrives, just to get myself a "seatbelt" for "just in case i screw-up".

Re: N900: JTAG or serial console over USB?
 

From what iI have read I believe the idea is you will not be messing with the boot loader so it should never be entirely bricked.

Presumably the boot loader has a recovery mode over USB?

Re: N900: JTAG or serial console over USB?
 

With jtag over usb available, it should be possible to even wipe the device entierly (including the uboot bootloader, which is most probably used) and still recover from it, provided one had kernel and os image.

I think that this what the flasher uses, though without an actual device (thanks for the delays...) it won't be possible to check.

Re: N900: JTAG or serial console over USB?
 

I guess you might be able to pile a whole bunch of stuff into initramfs. If that works let me know.

Re: N900: JTAG or serial console over USB?
 

Has anyone tried to clear mtd2?

Re: N900: JTAG or serial console over USB?
 

Doing it over the USB might be kinda hard (it would have to be a feature of the bootloader and I'm not sure JTAG could be done in such way), but do take a look at http://wiki.maemo.org/N900_Hardware_Hacking#Debug_ports

Re: N900: JTAG or serial console over USB?
 

The sheevaplug offers these options via built in JTAG and Serial interface hardware conected to its USB Peripheral interface. It's a nice approach, but the N900 doesn't do that.

Re: N900: JTAG or serial console over USB?
 

https://wiki.maemo.org/Updating_the_.../Cold_Flashing

Cold flashing (N900)

If the bootloader is deleted/destroyed with dd, then it is possible to recover it with a cold flash.....

Re: N900: JTAG or serial console over USB?
 

Will that work, if you wipe out all mtd devices to zeros with dd?


# cat /proc/mtd
dev: size erasesize name
mtd0: 00020000 00020000 "bootloader"
mtd1: 00060000 00020000 "config"
mtd2: 00040000 00020000 "log"
mtd3: 00200000 00020000 "kernel"
mtd4: 00200000 00020000 "initfs"
mtd5: 0fb40000 00020000 "rootfs"

I still have this problem. Flashing both rootfs and eMMC with PR1.3 images didn't fix the problem, so something still hides inside the phone which makes it buggy with this one operator's SIM-card.

Re: N900: JTAG or serial console over USB?
 

You can't solve that problem with reflashing. It is operators.