Modifying the Arnova 10 G2 custom firmware - Forum

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Modifying the Arnova 10 G2 custom firmware

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finless

Stanton, Ca

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2011/12/15 - 05:52

OK so I am new to all this but I gotta ask. Everywhere I read about adding contacts for Email, etc says to go to settings, accounts, contacts. But this unit does not have that in settings. Heck it does not even have an accounts setting unless I go into the Gmail app or other Google apps?

So I installed Google Voice and when I look at SMS messages I have, I can click on someone and add a contact. The latest Gmail I installed also allows you to open an Email and tap on the sender and add a contact. But when I go to compose an Email I have no contacts? I have no contacts icon anywhere?

So can someone explain why this is? I cant believe something as simple as contacts is not available or am I missing something stupid?

Bob

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2011/12/15 - 10:30

Contacts application is part of the Google Apps that are installed to certified devices.

It is not the case for Arnova tablets so Android Market and Google Apps need to be side loaded. Some apps require libraries or system modifications that are not currently working well on the Arnova G2, it will hopefully be fixed soon.

If you like our web site, applications and firmwares, feel free to support our site. Donations are used to pay the bills for our server hosting costs, development tools and purchase new tablets to support.

damo

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2011/12/15 - 10:39

Gmail does not have an add contact button like on traditional email, it auto enters the email as you enter it if they are in your contact list. A better program for email on Android is K9 or kaiten as these do have a button that directs you to your phone book and as long as you have synced your accounts to the phonebook than you just select your recipient. Obviously these tablets are not designed for a sim card so contacts are omitted. If you not bothered about using a dedicated email app than just log in to your Gmail with the web browser on your device.

Im not sure if the above mentioned programs allow you to save contacts in the program manually so you dont have to keep entering them?

finless

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2011/12/15 - 12:56

Thats a pain to login with a browser 🙁

BUT… I am "hacking" now. 😉

Using the RKtools (Wendal) I have started taking a look at the depacked stock IMG and comparing it to the latest rooted fw depacked IMG. I am finding some interesting things that are different.

Admin or anyone else that knows this stuff far better than me. Please teach me or point me in a direction to a resource that will please. I am tired of searching the XDA forum for any kind of generic tutorial on hacking the rom. They all seem to be dedicated to specific devices with no generic "this is how you go at it". At least not that I can find by searching that forum 🙁

So in the end the bootloader.bin is what controls write access to /system?

So I don't have to do 100's of file compares to see the differences between the two roms, can you give some tips on how to go at this?

If I can hack whatever is needed to make /system write permissions on the stock rom, we are done. I believe based on a ton of research the key is in files in the bootloader.bin? Is that correct? Help a n00b out to get going faster. I will share anything I do here on arctablet.

The beauty of this Arnova is the ability to bring back a bricked system so I am not afraid to play! 🙂

Bob

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2011/12/15 - 16:15

Yes, the boot.img is the firmware part that makes /system partition writable. It was written for some other RK2918 devices and I actually did not modify it.

I am working on a "more stock" firmware that will have latest Android Market (3.4.4) included but no /data storage partition size limit like on the actual custom firmware.

I will give some details on how it's done when I am finished.

In the meantime, knowing that you are already familiar with wendal tool, I recommend this reading:

http://wiki.archosfans.com/index.php?title=Dump_your_Home_Tablet_rom_and_create_a_custom_rom

finless

Stanton, Ca

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2011/12/16 - 17:39

COOL! thanks for the Wiki. Just what I needed 🙂

Bob

finless

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2011/12/16 - 22:57

Well I am getting places then not. Using Cramfsck are you able to exteact the boot.img?

I get errors. So is there some trick to that? Searching around on XDA, etc I see other guys doing this for older Archos tabs and it appears there is some header/footer issues?

FYI I am not a linux user e.g. I do not have a linux install on my machine... I am doing this using cramfsck tools that run under windows and I have also tried Cygwin shell for windows.

Bob

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2011/12/16 - 23:23

I am using Linux for most of the img manipulations. On Windows, I just use wendal tool to extract all the images from the update.img

Working with older RK2818 tabs is usually easier because their are better documented.

So far, I managed to extract the files from the boot img using this method:

http://www.slatedroid.com/topic/22169-official-x10-airpad-rom-image/page__view__findpost__p__238457

but I haven't spent time to rebuild the image from the extracted files.

I think Cygwin comes with tail and cpio, so you may get the boot image extraction to work on Windows.

finless

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2011/12/17 - 01:01

Yes also in the original wendal tool post there is a guy that explains how to pack/repack it. See post #8 and post #24

http://www.slatedroid.com/topic/19808-rk29xx-imagetools-v21/

Another guy updated the rk tools with a -k option which he says works

Again I am not a linux guy so it looks rather daunting and I need to compile the RKtools like rkcrc, etc. I have not compiled anything in linux before and my old unix days are long gone so I dont even remember these basics anymore 🙁

I wish Wendal would make a windows tool to unpack/repack the boot.img and add it to his kit. I am sure there will be one down the road.

So I assume that if I use the boot.img from the first rooted rom that it will have the memory space issue?

Thanks,

Bob

finless

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2011/12/17 - 02:58

Cool! Some success... 🙂

Using this process I was able to extract the boot.img in cygwin

use hexeditor to retrieve bytes 3..4 from header "3f 68 02 00" = 157759 decimal

FYI My boot.img byte 3..4 was 1f8b0300 = 204683 decimal. Did I do that correct admin?

dd if=boot.img of=initrd.gz skip=8 bs=1 count=157759

verify for errors gzip -t initrd.gz - there should be no errors

mkdir work;cd work;zcat ../initrd.gz|cpio -idm

However when I went to recompress, It bricked the tablet.

I used this to recompress

find . -exec touch -d "1970-01-01 01:00" {} ;

find . ! -name "."|sort|cpio -oa -H newc|gzip -n >../newinitrd.gz

./rkcrc.exe -p newinitrd.gz newboot.img

I got this from the post. The problem I had with the 2nd find command was that cygwin doesnt appear to have a user root?

Any ideas?

Oh and I got a compiled rxcrc.exe from this link:

http://topnotchtablets.com/misc/FirmwareUpdates/Wopadi7/TopNotchTablets_Wopadi7_Firmware_Tools_Package.zip

Bob

finless

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2011/12/17 - 06:03

More success 🙂

Turns out my remade boot.img was fine. After the process above the first 4 bytes of the faile say PARM. Just open the boot.img in a hex editor and change that to KRNL. Now my tablet boots fine and my boot.img works.

However even after editing the default.prop /system is still not writable 🙁

OK so what am I missing? I have confirmed the new flash on the tablet that uisng root explorer the default.prop is edited properly.

Bob

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2011/12/17 - 16:27

That's really great progress, thanks for sharing that with us.

Making a writable /system needs to do some changes in the boot image so the partition is mounted as read/write. (the system partition is normally a cramfs file system which is ready only).

I haven't checked in detail on how it's done with the boot image from our first custom firmware, checking init.rc file in boot image from this firmware should give you some pointers.

Anyway, using the boot.img from the first custom firmware will give you the space issue in /data.

Well, it looks like the toolchain is getting almost complete for firmware modification.

So far I prefered using Linux for all that, but I'll try to have a look under cygwin.

Let me know if you need any help with Linux binaries.

finless

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2011/12/17 - 18:19

OK I have hit a wall and not sure why. Yes I have gone through the rooted firmware and noted the changes made in init.rc. As you are aware using the Wendal tools you can take the stock firmware, replace the boot.ing from the rooted firmware, and you can make a working update.img. All good right?

If I unpack the stock firmware boot.img I can edit the default.prop and init.rc no problem. Rebuild the boot.img, rebuild the update.img with Wendal tools and the system boots.

Now here is the screwy part. If I make the changes to init.rc exactly like the changes in the rooted firmware init.rc, rebuild boot.img etc. It wont boot. So I decied just to copy all the stuff from the rooted firmware into my boot.img and still wont boot. Scratching my head for hours, I decided to do a test;

I unpacked the rooted boot.img and without touching it just repacked it and when done the new update.img will not boot. Just hangs on the Arnova screen.

Now the interesting thing. When you use the process I posted above to depack the boot.img from the rooted firmware gzip complains "unexpected end of file". However it does depack it best I can tell!!! However repacking it as posted above the system will not boot. So for sure there is something screwy with the rooted firmware boot.img. You cannot recreate it! I think it is corrupt in some way and thus I am not getting everything depacked that is needed to recreate it ANY IDEAS?

So basically that is where I am at. A wall I cant seem to figure out why I cant make the same changes to init.rc on stock FW that the rooted FW has.

Bob

finless

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2011/12/17 - 18:20

FYI since I have turned this into a rooting post, maybe change the title of the thread?

Bob

finless

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2011/12/17 - 20:27

So analyzing the init.rc file in the boot.img I see how they are getting write access to /system.

They are mounting the system cramfs to /sysro not to system. Then they are making a symbolic link to it which allows it to be RW.

The key edits to the init.rc are:

mkdir /sysro NOTE: Original has mkdir /system

mkdir /data 0777 system system

symlink /data/sysrw /system

OK then when they go to mount later in the init.rc file its:

mount cramfs mtd@system /sysro NOTE: original is mounted to /system

and this change

mount rootfs rootfs / rw remount NOTE: original was / ro

So this is clearly how they got root access from what I can see?

There are other changes here and there which all of them i have applied to an original rom boot.img init.rc file. Alas adding these changes the system will not boot. If anyone would like me to document all of the differences between stock init.rc and the rooted init.rc I would be glad to. I have them all marked up already after spending hours going over the differences.

This does not make any sense to me? As I said above if I use the Wendal tool to depack an original ROM and then just copy the rooted boot.img to it and remake update.img with Wendal tools it works. However if I depack the rooted rom boot.img and without touching it repack it and copy boot.img to an original depack rom, It wont boot. So something is very odd here. Again with the rooted boot.img, when you use the process posted above gzip complains "unexpected end of file". So not sure what gives 🙁

Bob