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


Nov 22, 2013
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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 =

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

# 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


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