Custom kernel and initramfs in SDE... to gain rooted android in my Archos 70 Internet

dogmaphobia · Dec 20, 2010

So I've finally kind of figured out several files in partition mmcblk0p1. Files named custom, init, and recovery are actually kernel and initramfs packed with 256 header. Information at offset 0x94 is length of kernel + header (256 bytes) and offset 0x98 is length of initramfs. Except of file init, contain additional size which I'm not actually understood.

By extracting init file, and modifying extracted initramfs, I can boot to android system with rooted state.
I've experimenting using unionfs got from somewhere in this forum and added files su and superuser.apk. I've added in init file inside initramfs.

Actually analyzing recovery files, we can get information regarding recovery program which mostly in bash script.

I've include my kernel and initramfs extracted from file init in mmcblk0p1. You can try for yourself only in Developer Edition, where you can flash your own kernel and initramfs.
Beware, I don't guarantee it will succeed... try for yourself

*Sorry, bad english...

$aur0n · Dec 20, 2010

Hi,

Is it not pointless to work on this squashfs, when we can use plain file/device partition on SDE (like Angstrom demo)? I guess (it's still theory - since I've just installed SDE) it's enough to create rootfs with copied everything from squashfs and /data - to make it fully writeable and rootable - and boot on it as /.
I'll give it a try later...

MoonPhantasm · Dec 20, 2010

No methods are pointless. Stop saying that. It's a progress to what we can do with the device.

Anyway, were you able to make that root work on the main OS, dogma?

$aur0n · Dec 20, 2010

MoonPhantasm said:
No methods are pointless. Stop saying that. It's a progress to what we can do with the device.

Ehh ok - but it makes thinks complicated, while we should straight everything up - to make upgrading smooth and easy

MoonPhantasm said:
Anyway, were you able to make that root work on the main OS, dogma?

As far as I can see in files - it should work.
Here's a diff of those init files (what was added)
out# diff init init.old
53,54d52
< CP=/bin/cp
< CHMOD=/bin/chmod
122,130d119
<
< # Create tempfs on /rootfs/home and unionfs with /rootfs/system
< $MOUNT -t tmpfs tmpfs $rootfs_path/home
< $INSMOD /lib/modules/unionfs.ko
< $MOUNT -t unionfs -o dirs=$rootfs_path/home=rw:$rootfs_path/system=ro unionfs $rootfs_path/system
< $CP /home/su $rootfs_path/system/bin/
< $CP /home/superuser.apk $rootfs_path/system/app/
< $CHMOD 6755 $rootfs_path/system/bin/su
< $CHMOD 755 $rootfs_path/system/app/superuser.apk

Booting from normal ext3 device requires some more changes - but gives us no 300MB (or similar) limit, allows to change boot parameters after kernel boots up (now on squashfs partition) etc. etc.

dogmaphobia · Dec 20, 2010

Yeah.. I'm able to get root with kernel and initramfs I've attached...

Darkseider · Dec 20, 2010

I am very excited about the prospects with SDE. Hopefully with some more poking and prodding and with Archos Froyo source released we will see some nice custom ROMs coming down w/ full root and a re-mapped file system in the coming months. I for one am hopeful that the dev community embraces the Gen8's w/ SDE and bakes up a nice serving of Gingerbread!

dogmaphobia · Dec 20, 2010

I was thinking that in recovery there's tool to flash initramfs and kernel which formed in file custom in mmcblk0p1. If we can replace destination to init (not custom). I think we can force booting to our new change, without entering to recovery mode first.

But, I still don't want to break anything in partition mmcblk0p1

.

Also, if we can modifying squashfs file with new one, without script checking the file (I think is on cramfschecker program); we can have custom rootfs itself replacing androidmerged.squashfs.secure....

Just the thought...

d34thd34l3r · Dec 20, 2010

Keep up the good work guys!

chrulri · Dec 20, 2010

just copied the content of the squashfs in an ext3 image and modified the init and mountpoints.

will report later after some testing

$aur0n · Dec 21, 2010

Heh.. I've just did the same - but on ext3 partition of sd card. Not luck yet to full boot... yet...

chrulri · Dec 21, 2010

me neither. don't have time for more testing today and tomorrow, but soon I have a lot of spare time

edit: currently running kernel and initramfs of dogmaphobia, works great so far

denoxster · Dec 21, 2010

Let me know when you guys news beer on your break, its on me.
Keep up the good work.

nimrodity · Dec 21, 2010

its too bad i am too dumb to understand all of what you are saying.
Does this mean rhe archos can be booted with root?
is it then rooted on the normal android firmware i use at the moment or on something else?
If yes how exactly do i get this to work and will there be a easier version for people like me who dont know that much about that kind of things.
and sorry again if my questions are dumb,i just want to try to get it.

$aur0n · Dec 21, 2010

nimrodity said:
Does this mean rhe archos can be booted with root?

Yes - but with SDE installed (and voided warranty - unless Archos claims so)

nimrodity said:
is it then rooted on the normal android firmware i use at the moment or on something else?

We are trying to boot oryginal Archos-Android on writtable disk (then it will be fully rooted - on OS level at least). dogmaphobia prepared initrd (first stage boot - lets say) that mounts part of original dir tree as RW and installs SU (switch to root) tool.

nimrodity said:
If yes how exactly do i get this to work and will there be a easier version for people like me who dont know that much about that kind of things.

Probably yes, this one is not so hard either - but it's really just a first step, so I recommend to wait.

Uejji · Dec 21, 2010

This is freaking awesome. Since 2.0.71 disabled temproot I haven't been using my 101 very much other than poking around in Angstrom.

I voided the warranty on every other Android device I own for root, and I sure don't mind doing it on my 101 either.

nimrodity · Dec 21, 2010

@$aur0n
thx for the explanation.
Since i am please ight now ho the archos works,i ca wait a while till something new comes up.
so no hurry,we all saw how achos handled that with an unfinished bugged fimware

nickwarn · Dec 21, 2010

this is great news, im so looking forward to the future with a fully rooted device. And all the benefits that comes with that,maybe some custom roms maybe even cyanogen mod, A2SD, custom kernels and Gingerbread. If this comes thru it blows this wide open. Keep up the good work

chrulri · Dec 21, 2010

@dogmaphobia you've written kernel size was at 0x94 and initramfs size at 0x98 but I don't get it. 2byte value (db70) at 0x94 results in 56176 and (db700021) ist far too much for kernel size. same weird result for initramfs.

how did you extract initramfs and kernel from this mmcblk0p1/init file? may post a shell script?

$aur0n · Dec 21, 2010

I've checked my "custom" file - on pos. 94 i have unsigned 32bit (8 bits) value "2218864" - witch might be ok, since 2218864-256=2218608 - and that's exactly the size of kernel that dogmaphobia send (and it's bootable).

On pos. 98 I have value "833767" (8 bit stream like before) - that's look also quite ok.

ps. and you should be able to extract it with dd (dd if=custom of=whatever bs=1 skip=245 count=2218608) - it's slow with bs=1 but...

Unmensch · Dec 21, 2010

Heym I mounted the rootfs.img as loop, put the two files from dogmaphobia in /boot and copied the image back to internal memory, but wasn't able to boot from this image. Any tips?

Custom kernel and initramfs in SDE... to gain rooted android in my Archos 70 Internet

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