Compiling the Linux Kernel for the Kindle

[yifanlu]

After three days and tons of googleing, I've compiled, set up, and installed the kernel for Kindle. Directions as follows:

Part 1: Prerequisites

• Get a root shell of your Kindle. If you don’t know, Google “usbNetworking”
• A Linux computer for compiling code
• Amazon’s sources for your version of the Kindle: http://www.amazon.com/gp/help/custom...deId=200203720
• An ARM cross-compiler. You can compile Amazon’s code, or if you’re lazy, use CodeSourcery’s precompiled toolchain: http://www.codesourcery.com/sgpp/lite/arm
• The following packages, get them from your distro’s repo: libncurses-dev (for menuconfig), uboot-mkimage (for making the kernel image), and module-init-tools (depmod)

Part 2: Compiling the kernel

1. Extract the source to anywhere. If you can’t decide, use “~/src/kernel/” and “cd” to the source files.
2. Now, you need to configure for the Kindle, type “make mario_mx_defconfig“
3. Edit the “.config” file and look for the line that starts with “CONFIG_INITRAMFS_SOURCE“. We don’t need that, delete that line or comment (#) it out.
4. Here’s the part were you make all your modifications to the kernel. You might want to do “make menuconfig” and add extra drivers/modules. I’ll wait while you do that.
5. Back? Let’s do the actual compiling. Type the following: “make ARCH=arm CROSS_COMPILE=~/CodeSourcery/Sourcery_G++_Lite/bin/arm-none-linux-gnueabi- uImage”. This will make the kernel image. I assume you installed CodeSourcery’s cross compiler to your home folder (default). If your cross compiler is elsewhere, change the command to match it.
6. Compile the modules into a compressed TAR archive (for easy moving to the kindle): “make ARCH=arm CROSS_COMPILE=~/CodeSourcery/Sourcery_G++_Lite/bin/arm-none-linux-gnueabi- targz-pkg” (again, if your cross compiler is installed to a different location, change it).
7. For some reason, depmod refuses to run with the compile script, so we’re going to do it manually. Do the following “depmod -ae -F System.map -b tar-install -r 2.6.22.19-lab126 -n > modules.dep” Change 2.6.22.19-lab126 to your compiled kernel version.
8. Open modules.dep up with a text editor and do a search & replace. Replace all instances of “kernel/” with “/lib/modules/2.6.22.19-lab126/kernel/” (again, use your version string). I’m not sure this is needed, but better safe then brick.
9. Now copy arch/arm/boot/uImage, linux-2.6.22.19-lab126.tar.gz (or whatever your version is), and modules.dep to an easy to access location.

Part 3: Installing on Kindle

1. Connect the Kindle to your computer, and open up the storage device. Copy the three files you moved from the previous part to your Kindle via USB.
2. This part is mostly commands, so get a root shell to your Kindle, and do the following commands line by line. Again, anywhere the version string “2.6.22.19-lab126” is used, change it to your kernel’s version. Explanation follows.

mv /mnt/us/linux-2.6.22.19-lab126.tar.gz /mnt/us/modules.dep /mnt/us/uImage /tmp
mv /lib/modules /lib/modules.old
cd /tmp & tar xvzf /tmp/linux-2.6.22.19-lab126.tar.gz
mv lib/modules /lib/
chmod 644 modules.dep
mv modules.dep /lib/modules/2.6.22.19-lab126/
/test/flashtools/update-kernel-both uImage
sync
shutdown -r now

Wow, that’s a lot of commands. What did that do? Well, line by line:

1. Move the files we compiled to the temp folder. That way, we don’t have to clean up.
2. Back up the old kernel modules
3. Go to the temp folder and untar the modules
4. Install the modules
5. Correct the permissions for the modules.dep file (in case something happened after copying from your computer)
6. Move the module dependencies list to it’s correct folder.
7. Flash the kernel (I don’t know why it has to be flashed twice to two different partitions, but if you don’t, it won’t load, maybe sig checks?)
8. Make sure everything is finished writing
9. Reboot

Source: Myself (http://www.yifanlu.com/2010/07/26/ha...ng-the-kernel/)

EDIT: Deleted question, inserted directions

[NiLuJe]

Haven't tried.

One fun thing to try would be the ethernet+mass storage combo gadget USB driver. (Not sure it was there @ 2.6.22 though, but that shouldn't be too messy to backport).

[yifanlu]

Ok, I almost have the kernel compiled (amazon adds some extra files (I don't know what yet) to the initramfs that isn't included with the source, in order to get them, I need a copy of Kindle's current kernel). Anyways, bigger question, how do I get the kernel to load after compiling it? Do I HAVE to do a serial connection and give it to uBoot, or can something be done within shell to load it?

[yifanlu]

In case anyone wants to compile the kernel, here's what you have to do (I might do a big write up one day, but for now):

I'm assuming you're a developer or linux hacker and have all the usual development tools and dev packages installed and knows how to compile stuff.

1. Get a cross compiler for ARM, you can compile your own with Amazon's provided source (gcc, libc, binutils, etc), or install a pre-compiled one: http://www.codesourcery.com/sgpp/lite/arm
2. Get uboot-mkimage from any repository
3. Set to compile for Kindle's MX3 arch, do the following command

make mario_mx_defconfig

4. Amazon adds some extra files to the initramfs, I can't find these files right now, and I don't know the side effect of not having them. For now, just ignore those files. Edit ".config"
Look for

CONFIG_INITRAMFS_SOURCE="../../initramfs/skeleton.list ../../initramfs/image/"

Change to

CONFIG_INITRAMFS_SOURCE=""

5. Do whatever you want to the kernel, the most popular choice would be to add additional drivers and modules to the kernel, so to do that, do:

make menuconfig

6. Compile the kernel, do the following

make ARCH=arm CROSS_COMPILE=~/CodeSourcery/Sourcery_G++_Lite/bin/arm-none-linux-gnueabi- uImage

7. Compile the modules

make modules

8. Copy everything over to the kindle, install modules to their respective locations (/lib/modules/) and copy uImage to root (/)
9. do

/test/flashtools/update-kernel-both /uImage

Reboot and pray

[NiLuJe]

Not sure. I seem to remember that they're stored in a dedicated partition, and that there's two (maybe three?) different kernels (one for the recovery/update process). But you'd better check yourself .

I guess a usbnet shell should be enough to extract the current initramfs, but, yeah, it's probably safer to have a serial console available in case things don't go as planned .

[yifanlu]

Ok, I got it, kernel compiled into correct format and flashed.

[NiLuJe]

Nice! Thanks for the info

[zetareticuli]

How can you add wifi support via a kernel compilation? Does the hardware support it? Just wondering...

[yifanlu]

So, yea, after dumping messages, I see "Linux version 2.6.22.19-lab126 (root@ubuntu) (gcc version 4.4.1 (Sourcery G++ Lite 2010q1-202) ) #1 PREEMPT Sun Jul 25 12:25:32 UTC 2010"

Yeah, my kernel is loaded! Then

100725:211602 ppp_generic: disagrees about version of symbol skb_copy_bits
100725:211602 ppp_generic: Unknown symbol skb_copy_bits
100725:211602 ppp_generic: disagrees about version of symbol __netif_schedule
100725:211602 ppp_generic: Unknown symbol __netif_schedule
100725:211602 ppp_generic: disagrees about version of symbol unregister_netdev
100725:211602 ppp_generic: Unknown symbol unregister_netdev
100725:211602 ppp_generic: disagrees about version of symbol skb_dequeue
100725:211602 ppp_generic: Unknown symbol skb_dequeue
100725:211602 ppp_generic: disagrees about version of symbol skb_pull_rcsum
100725:211602 ppp_generic: Unknown symbol skb_pull_rcsum
100725:211602 ppp_generic: disagrees about version of symbol skb_under_panic
100725:211602 ppp_generic: Unknown symbol skb_under_panic
100725:211602 ppp_generic: disagrees about version of symbol kfree_skb
100725:211602 ppp_generic: Unknown symbol kfree_skb
100725:211602 ppp_generic: disagrees about version of symbol __alloc_skb
100725:211602 ppp_generic: Unknown symbol __alloc_skb
100725:211602 ppp_generic: disagrees about version of symbol skb_queue_tail
100725:211602 ppp_generic: Unknown symbol skb_queue_tail
100725:211602 ppp_generic: disagrees about version of symbol skb_over_panic
100725:211602 ppp_generic: Unknown symbol skb_over_panic
100725:211602 ppp_generic: disagrees about version of symbol register_netdev
100725:211602 ppp_generic: Unknown symbol register_netdev
100725:211602 ppp_generic: disagrees about version of symbol free_netdev
100725:211602 ppp_generic: Unknown symbol free_netdev
100725:211602 ppp_generic: disagrees about version of symbol skb_queue_purge
100725:211602 ppp_generic: Unknown symbol skb_queue_purge
100725:211602 ppp_generic: disagrees about version of symbol __pskb_pull_tail
100725:211602 ppp_generic: Unknown symbol __pskb_pull_tail
100725:211602 ppp_generic: disagrees about version of symbol netif_rx
100725:211602 ppp_generic: Unknown symbol netif_rx
100725:211602 ppp_generic: disagrees about version of symbol alloc_netdev
100725:211602 ppp_generic: Unknown symbol alloc_netdev
100725:211602 ppp_generic: disagrees about version of symbol skb_queue_head
100725:211602 ppp_generic: Unknown symbol skb_queue_head
100725:211602 modprobe: FATAL: Error inserting ppp_generic (/lib/modules/2.6.22.19-lab126/kernel/drivers/net/ppp_generic.ko): Unknown symbol in module, or unknown parameter (see dmesg)
100725:211602 lipc-get-prop[2969]: I lipc:giprop=localTimeOffset, source=com.lab126.wan:Get int property
100725:211602 system: I loginfo:ltoget:lto=-18000: local time offset has been read
100725:211602 lipc-set-prop[2978]: I lipc:siprop=wakeUp, source=com.lab126.powerd, value=1:Set int property
100726:021602 powerd[1767]: W def:unhandle:state=e_wake_up, evt=ACTIVE:Unhandled event e_wake_up in state ACTIVE
100725:211602 lipc-set-prop[2978]: I lipc:ssprop=wakeUp, source=com.lab126.powerd:Set string property
100725:211602 powerd[1767]: W lipctrop=setwakeUpStr:Property found but with a differnt type
100725:211602 lipc-set-prop[2978]: E def:fail:source=com.lab126.powerd, prop=wakeUp:Failed to set property
100725:211603 pppd[2925]: This system lacks kernel support for PPP. This could be because the PPP kernel module could not be loaded, or because PPP was not included in the kernel configuration. If PPP was included as a module, try `/sbin/modprobe -v ppp'. If that fails, check that ppp.o exists in /lib/modules/`uname -r`/net. See README.linux file in the ppp distribution for more details.

Dammit, I forgot to copy the new modules.


@zetareticuli, before compiling the kernel, if you do "make menuconfig", you get a screen with everything you want supported. However, it has to work with the hardware, and so far I only see USB ports and a mini pci-e port (for the wwan). So, let's say I have a custom WWAN card that I want to use on the kindle. I select it in menuconfig, and install it, then the kindle will see it.

[yifanlu]

Ugh, I need to restore the original kernel before installing the new one. Can someone give me. Quick guide to kindle firmware tool? I understand it's something like this:
1) create. .sh file
2) add other files
3) use tool with m option
However, what do I name the sh file?

[zetareticuli]

Yifanlu, thanks for the info. I wouldn't mind collaborating with you on these projects but I have to get a Kindle first. Which one do you have?

[yifanlu]

Originally Posted by zetareticuli

Yifanlu, thanks for the info. I wouldn't mind collaborating with you on these projects but I have to get a Kindle first. Which one do you have?

Kindle 2 US

[zetareticuli]

Alright. So I just bought a refurbished Kindle 2 to start testing all this. One thing that I really want to work on is the addition of a virtual SD card. With a virtual SD card, there would be little need for a real SD port. You just mount the virtual SD card that would read from, say, a web folder. Also, I would like to create a better PDF viewer. Something as close as possible to the PDF viewers that run on personal PCs.

[yifanlu]

Originally Posted by zetareticuli

Alright. So I just bought a refurbished Kindle 2 to start testing all this. One thing that I really want to work on is the addition of a virtual SD card. With a virtual SD card, there would be little need for a real SD port. You just mount the virtual SD card that would read from, say, a web folder. Also, I would like to create a better PDF viewer. Something as close as possible to the PDF viewers that run on personal PCs.

Why would you need a virtual SD card? Kindle mounts on the computer as a FAT32 storage device. Also, the frontend is coded in Java, so it has nothing to do with the kernel.

[NiLuJe]

@yifanlu: I guess you can extract the latest default kernel from the official update file, if you haven't got a backup.

As for the packer, the shell script don't need to have a specific name, AFAICT, the update tool run *every* sh file in the binfile, sequentially (ie. 0000-patches.sh, then 5555-kernel.sh).

@zetareticuli: Also, unless you're using a custom SIM, that would, again, break Amazon's terms, because you're hijacking the 3G connexion. And, btw, you don't need to touch the kernel to do 'virtual' (userland) mounts, Fuse is installed (and used by Amazon).