Archos 101, an open tablet ?
As well as some of us, I recently acquired a “tablet”. This little device sold by Archos was intended to be freely hackable, meaning that archos will provide means to install and boot another OS than the one currently shipped: Android.
Episode 1: the unpacking
Once I received the tablet, I went through unpacking and booting Android for the very first time. This part is very common.
I just confirmed that Froyo wasn’t meant for tablets: it is slow, crashes and well I don’t want to use my tablet like a phone, so it’s not fit for me.
Episode 2: SDE install
Archos released their modified firmware for software developpers including the following changes (as far as my knowledge goes):
- A modification of the boot process (now dual boot is possible)
- A warranty void (that was the nice surprise)
- Ångström linux with the GPE desktop environment
After installing the new image and booting in Ångström for the first time, one come to realise that there is no WiFi, sound or backlight support. Sound comes after playing with alsamixer and setting the speaker to on.
I looked a bit into WiFi and I found a tutorial for the archos 5 which seemed to be usable for the 101. Unfortunately, it requires two kernel modules (tiwlan_drv and sdio), a firmware file and some homemade scritps. Even if I managed to build the first of the two modules, I’m missing sdio. The result for now is: no WiFi till I have the second one.
Episode 3: How does it boot, really ?
I was then curious to see how the boot process worked. As usual with linux, at the begin there’s two things; an initram filesystem and the kernel. The archos bootloader allows you to update these two ones via the recovery section of the boot menu.
But what partition does it run on ? I couldn’t find one at first, and then I noticed in my data partition (
/mnt_data) a file called rootfs.img. That’s explicit: this is then the file containing the filesystem to run Ångström on.
After a short conversation on the #archos channel (freenode), I learnt that there were a hidden partition (raw format) containing 3 kernels (one for Android, one for Linux and the last is recovery) where the archos utility writes the newly flashed Linux kernel.
What happens when you replace the rootfs image by some other file with the same name ? For instance one taken from the Ubuntu ARM project page ?
My answer for now is this:
Don’t get too excited though, nothing works here except X and the screen. No touchscreen, no USB, no hardware button. But good point is: the only thing that is really missing is a proper kernel and initramfs.
Little question: I just replaced the rootfs image, so why the hell is it not recognizing my average peripherals that are working with Ångström ? The kernel image shouldn’t have changed! Maybe my sources have it wrong, maybe there’s something fishy I’m not yet aware of…
Next Episode(s) in the next post.