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kernel
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1) download source tree of android JB from Google.

2) add mediatek folder and makeMtk file. 

3) replace kernel,external,prebuilt,system,bootable folders.

4) build kernel by 
  . build/envsetup.sh

  choosecombo 1 1 3

5) ./makeMtk simcom75_twn_cu_jb new kernel uboot


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