Mediatek and their customers have still not gotten into the habit of complying with the GPL license, and releasing the relevant source code such as the Linux kernel. There appears to be at least one smartphone, Wiko Stairway, where the Linux kernel has been released, and chrmhoffmann, a members of XDA developers forums, has even released on unofficial CyanogenMod 11 ROM (Android 4.4.2 Kit Kat) for the device.
There are three source repositories for the Linux kernel, “android device“, and Android.
I’ve only looked into the kernel which is version 3.4.5. Mediatek has apparently messed up the Linux kernel quite a bit, and you’ll have to do some funny things to build the kernel, and all Mediatek options in menuconfig are in a sub-section called “Mediatek Properitary Configuration” (sic.), and it’s not possible to simply go to System Type menu to change the processor type for instance.
Let’s get the source first:
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git clone https://github.com/chrmhoffmann/android_kernel_wiko_stairway cd android_kernel_wiko_stairway/ ls bionic kernel mediatek README |
So together with the kernel, we’ve got the bionic library, and the modifications done by Mediatek in the mediatek directory. The Makefile is this Linux kernel is set to use the Android gcc toolchain (arm-linux-androideabi-gcc), but I tried to build the kernel with CROSS_COMPILE=arm-linux-gnueabihf- instead, and it failed along the way with the following error:
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fs/file_table.c: In function 'get_empty_filp': fs/file_table.c:36:20: error: inlining failed in call to always_inline 'fd_show_open_files': function body not available extern inline void fd_show_open_files(pid_t pid, struct files_struct *files, struct fdtable *fdt); ^ fs/file_table.c:160:36: error: called from here fd_show_open_files(pid, files, fdt); ^ make[1]: *** [fs/file_table.o] Error 1 make: *** [fs] Error 2 |
This is from code added by Mediatek, and at first I just disabled it, but a similar problem occurred in the wlan drivers. Some research indicated in may be a toolchain problem, so I’ve installed the latest Linaro Android toolchain and added it to my path:
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wget http://releases.linaro.org/14.02/components/android/toolchain/4.8/android-toolchain-eabi-4.8-2014.02-x86.tar.bz2 tar xvf android-toolchain-eabi-4.8-2014.02-x86.tar.bz2 export PATH=$PATH:~/edev/Mediatek/android-toolchain-eabi/bin/ |
And started the build:
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cd kernel TARGET_PRODUCT=wiko MTK_ROOT_CUSTOM=../mediatek/custom/ make -j8 |
Same error. So I gave a last try with an older Linaro Android toolchain using gcc 4.6, and this did the trick:
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LD [M] mediatek/platform/mt6589/kernel/drivers/devapc/devapc.ko LD [M] mediatek/platform/mt6589/kernel/drivers/dual_ccci/ccci_plat.ko LD [M] mediatek/platform/mt6589/kernel/drivers/devinfo/devinfo.ko LD [M] mediatek/platform/mt6589/kernel/drivers/gpu/pvr/mtklfb.ko LD [M] mediatek/platform/mt6589/kernel/drivers/gpu/pvr/pvrsrvkm.ko LD [M] mediatek/platform/mt6589/kernel/drivers/masp/sec.ko LD [M] mediatek/platform/mt6589/kernel/drivers/videocodec/vcodec_kernel_driver.ko AS arch/arm/boot/compressed/piggy.gzip.o LD arch/arm/boot/compressed/vmlinux OBJCOPY arch/arm/boot/zImage Kernel: arch/arm/boot/zImage is ready |
As for the current CM11 ROM, phone calls, SMS, data (2G, 3G), Wi-Fi, audio, and most sensors are working fine, but there’s still more work to do as the second SIM card, the camera, hardware video decoding, GPS, Bluetooth, FM radio and some MTK specific features are not supported yet. It may not be wise to try it on MT6589 hardware other than Wiko Stairway, as you may brick your device.
Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.
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