Hi, Frantisek,
Thanks for your answer.
Cheers,
Paule
----- Original Message -----
From: "Frantisek Dufka" <[EMAIL PROTECTED]>
To: "Paule Ecimovic" <[EMAIL PROTECTED]>
Cc: <[email protected]>
Sent: Friday, February 16, 2007 9:38 PM
Subject: Re: [maemo-users] Booting from MMC as a de-bricking method
Paule Ecimovic wrote:
I am most concerned about the bricking scenarios resulting from flashing
a 770 to set it into R&D mode, where the 770 sometimes bricks after
rebooting.
Never hear of this, is this real? What you see on the screen when it
boots? How many seconds exactly boot takes since poweron before it reboots
again (i.e. in which step mentioned below it stops)?
Are there bricking scenarios in this reboot situation which involve
corruption beyond MMC reboot?
I'm not sure what you mean by this (and was not answered already). Let's
explain how device boots:
1. bootloader (probably at least two of them, one loads another)
initializes some hardware, checks if flasher is connected and finally
loads linux kernel from /dev/mtd2. Some small bootloader is stored either
in masked ROM or NOR flash directly on OMAP chip, the second one is stored
in (NAND) flash - /dev/mtd0
2. linux kernel starts, initializes hardware and runs linuxrc from initfs
partition (/dev/mtd3)
3. initfs (uclibc based system) starts dsme and bme, loads wlan and bt
firmware, checks root device name stored in flash (=config partition
/dev/mtd1)mounts it and continues boot from that device (via pivot_root
[1]). This is where bootmenu modification lives too, it simply allows you
to select different root device then stored by flasher.
4. /sbin/init starts from the root device and normal linux system boots
via rc scripts
This means that if bootloader (/dev/mtd0) or kernel (/dev/mtd2) is
corrupted or maybe even config partition (bootloader probably uses it too
to store some data - MAC address? list of bad flash blocks? partition
layout?) then the device is 'bricked' and bootmenu cannot help since it
has no chance to run. Only reflash over usb (or serial) can help.
But normal bricking done by most users and mentioned in previous mail
means corrupting rootfs (/dev/mtd4) and this can be solved by booting from
anything else (=mmc) via bootmenu.
Any chance of hard-disk based ITOS for Nokia Internet Tablet's.
Harddisk would not solve anything. Same like when you corrupt your bios on
PC.
but it would allow rebooting in various modes and under various privledge
schemes without the threat of irreparable bricking.
Harddisk is not any better than mmc, both are lock devices used by linux
kernel.
Regards,
Frantisek
1. http://www.die.net/doc/linux/man/man8/pivot_root.8.html
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