A noobie with some questions about flashing/booting...

[Guest chuci]

Hi all, first a bit of background:

I'm the proud owner of a Tab and a bit of a tinkerer as well: I have a Nokia N900 and am part of the community working towards full MeeGo support for that (well, and other ARM devices too!). My Tab is the first Android device I've owned and I'm slowly learning my way around Android both for fun and profit, day to day use but also with a view to trying to get MeeGo booting as well. To that end I need a little guidance:

I've rooted the device (z4root), I've got the SDK installed on my computer and have adb working. So far, so good. The next thing I was going to look into was booting a different kernel and this is where I've become a bit stuck. adb reboot recovery will bring the device to the recovery console but adb reboot bootloader just reboots the device as normal. After a fair bit of reading around it seems that HTC devices interact with a command called fastboot which can boot from an arbitrary kernel & initrd:- or at least that's how I understand it. Is there something equivalent for Samsung devices? Or have I misunderstood it altogether: is the only way to achieve something like this is a custom image that looks sufficiently Android-ish that can then do a custom init into something else (sadly there is no kexec support for MeeGo).

Regarding booting, the purpose of the recovery mode is clear to me, but what about the 'Downloading Target' mode (power + volume up IIRC). What does that do?

Where I'd like to get to is to be able to boot the device (possibly only with the help of a computer) into MeeGo on an SD card; that way I can play with MeeGo but not in a destructive way to the Tab. FWIW, I've already been able to chroot into a custom MeeGo image for the N900 just fine so I'm confident there won't be any userspace problems. I'm just struggling to get my head round how the thing boots and how to non-destructively get it to run the OS from the SD card.

Any guidance, pointers and answers to my dumb questions would be greatly appreciated, and if I've posted this in the wrong place I apologise, mods, please move it to somewhere appropriate.

Many thanks.

Steph

Edited December 19, 2010 by chuci