Thread: PR 1.3. Leaked?
View Single Post
joerg_rw's Avatar
joerg_rw is offline joerg_rw
2010-10-20 , 21:17
Posts: 2,222 | Thanked: 12,651 times | Joined on Mar 2010 @ SOL 3
#52
Originally Posted by sjgadsby View Post
I'm with you except for this. NOLO is software that should be approached with extreme caution. An N900 recoverable only via JTAG is effectively bricked for most people.
Jacekowski claims ROM-Bootloader (the level-0 bootloader that probably can never get hosed) on N900 has code to do a cold flash via USB, he even says he did it iirc
For the original claim it'd be impossible to kill N900 via sw - ohohoh, you got no idea how easily you can break things like CPU or NAND bad block management or a dozen other things via software

Originally Posted by woody14619 View Post
Does this image change the loader? Has anyone confirmed if the alternate bootload stuff is in the W36 image?
NOLO will not be changed on next frimware update, I heard. Alternate bootload stuff for sure won't be in next maemo image, this info was a big misconception. Next maemo kernel will have working kexec, which would allow to boot a alien OS from within a working booted maemo system - so no real dualboot at all. Anyway Meego will use chainloader booting NOLO->uBoot->[maemo/meego/arbitrary other system], so it's not related to kexec at all and can be implemented any time.

Originally Posted by woody14619 View Post
One thing that does confuse me though: If you use the "hold u while booting" technique, doesn't that allow you to reflash the loader as well? I though the whole point of having the hardware shortcut was to force the load from ROM, which (while a set/old version) can always flash the entire device, loader included.
No, holding 'u' - for all I know - just forces NOLO into flashing mode. Yes, a working NOLO can flash itself, means replace the NOLO program code stored in NAND with a new one. This won't help nevertheless if NOLO is hosed - see above for for ROM-BL and coldflashing though.

Originally Posted by woody14619 View Post
This was one of the nice bits built into the second gen of the Neo FreeRunner (vs the 1973). If you held a hardware key down at startup it would boot completely from ROM, allowing you to always recover from a bad software load, since there was no way to over-write the ROM code. The ROM version had speed issues (only negotiated USB 1), but it was a safe fallback if one needed it because they hosed the loader in NAND.
It was NOR-flash, not ROM. You could change NOR with a debug board. NOR has a secondary uBoot bootloader, which is the exact counterpart of NOLO/ROM-BL (1st/2nd uBoot), thus allowing you to flash a fresh primary NAND uBoot and rootfs to NAND. The system itself never had any shadow copy anywhere.

@Mohammad: afaik N900 has JTAG. It's just you don't usually need it (see ROM-BL coldflash) and usually don't have the tools to access and operate it


Warnings about leaked PR1.2 back when were absolutely serious, as modem FW was updated with an incompatible version, which left you with a broken phone functionality when downgrading from PR1.2 to an older version

cheers
jOERG
__________________
Maemo Community Council member [2012-10, 2013-05, 2013-11, 2014-06 terms]
Hildon Foundation Council inaugural member.
MCe.V. foundation member

EX Hildon Foundation approved Maemo Administration Coordinator (stepped down due to bullying 2014-04-05)
aka "techstaff" - the guys who keep your infra running - Devotion to Duty http://xkcd.com/705/

IRC(freenode): DocScrutinizer*
First USB hostmode fanatic, father of H-E-N
 

The Following 9 Users Say Thank You to joerg_rw For This Useful Post: