[GUIDE] How to disable force encrypt and speed up your nexus 9

Discussion in 'Nexus 9' started by rhcp011235, Dec 14, 2014.

  1. rhcp011235

    rhcp011235 Developer
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    Well,

    I bit the bullet and I bought a nexus 9 and i actually have a nexus 6 coming soon too. Im not sure how long I will keep these devices but I guess as I mess around Ill post some stuff here.

    First thing for me, was to disable the encryption to speed up this tablet almost 200X fold.

    I was looking at people posting repacked kernels and I am not really the type that says OK, and flashes and goes on. i want to know how/why and how I can do it myself.

    Well, the answer is quite simple. This flag is inside the nexus9 boot.img (and the file inside the ramdisk)

    the file name is = fstab.flounder (somehow some people are able to repack these images)

    I picked to do it from source code.

    So you would sync up to the latest for 5.0.1

    your dir may vary but mine is =
    /Volumes/Android/aosp/device/htc/flounder

    This is the device folder and it contains the file we need to edit.

    Code:
    # Android fstab file.
    
    #<src>                                                  <mnt_point>         <type>    <mnt_flags and options>                       <fs_mgr_flags>
    
    # The filesystem that contains the filesystem checker binary (typically /system) cannot
    
    # specify MF_CHECK, and must come before any filesystems that do specify MF_CHECK
    
    
    
    /dev/block/platform/sdhci-tegra.3/by-name/APP   /system             ext4      ro                                                    wait
    
    /dev/block/platform/sdhci-tegra.3/by-name/VNR   /vendor             ext4      ro                                                    wait
    
    /dev/block/platform/sdhci-tegra.3/by-name/CAC   /cache              ext4      noatime,nosuid,nodev,nomblk_io_submit,errors=panic    wait,check
    
    /dev/block/platform/sdhci-tegra.3/by-name/UDA   /data               f2fs      noatime,nosuid,nodev,errors=recover    wait,check,encryptable=/dev/block/platform/sdhci-tegra.3/by-name/MD1
    
    /dev/block/platform/sdhci-tegra.3/by-name/UDA   /data               ext4      noatime,nosuid,nodev,nomblk_io_submit,errors=panic    wait,check,encryptable=/dev/block/platform/sdhci-tegra.3/by-name/MD1
    
    /dev/block/platform/sdhci-tegra.3/by-name/LNX   /boot               emmc      defaults                                              defaults
    
    /dev/block/platform/sdhci-tegra.3/by-name/SOS   /recovery           emmc      defaults                                              defaults
    
    /dev/block/platform/sdhci-tegra.3/by-name/MSC   /misc               emmc      defaults                                              defaults
    
    /dev/block/platform/sdhci-tegra.3/by-name/EBT   /bootloader         emmc      defaults                                              defaults
    
    /dev/block/platform/sdhci-tegra.3/by-name/PST   /persistent         emmc      defaults                                              defaults
    
    /dev/block/zram0 
    
    So simply by changing the force to encrypt able fixes the issue.

    now you go to your crooot (main android build system)

    and you type in
    . build/envsetup.sh
    lunch aosp_flounder-userdebug
    make -j 8 bootimage

    after awhile you shall get a bootimage. and you can flash it to your nexus9 and you don't need to wait for people to post re-packs. you can just sync up + do as described and poof.

    Now one other thing I noticed, The nexus9 kernel is prebuilt and so is the DTB. so you can only modify the ramdisk from AOSP level. I am assuming the real kernel is someplace else. I really have not looked for it since I don't really do kernel work. But, I found this odd, normally you build the kernel and all. Not in this case!

    Hope this helps some. It helped me
     
  2. rhcp011235

    rhcp011235 Developer
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