Reboot-Persisting All-User-Access USB Serial Port on Froyo

I turned the USB into a serial port. Then, I noticed it wasn't usable without superuser permissions. Recently, I got some great information from a former Android coder and have now have a permanent fix that persists on reboot with Android 2.2 (Froyo).

First, I edit init.mahimahi.c
(mahimahi is the board for Nexus One (aka HTC Passion), if you're working on another HTC device, you'll need to edit the right file for your device).

$ gedit path/to/device/htc/passion/init.mahimahi.c

I put the following at lines 64 and 65.

#mwk: Enable Serial Port for all users
chmod 0777 /dev/ttyMSM0

I run lunch.

~/mydroid$ . build/envsetup.sh
~/mydroid$ lunch

I choose option 4 (full_passion)

I plug in a Nexus One and extract the device info.

~/mydroid$ cd device/htc/passion
~/mydroid/device/htc/passion$ ./extract-files.sh

I re-make the AOSP.

~/mydroid/device/htc/passion$ cd ../../..
~/mydroid$ make

I get the phone in bootloader mode (the fast way).

$ adb reboot-bootloader

I flash the device. (On this website, step 14 didn't work for me, so I now run the command this way.)

~/mydroid/out/host/linux-x86/bin$ sudo ./fastboot -p passion -w flashall

On the phone, I enable applications from unknown sources.

Settings--> Applications --> Unknown sources --> checked

Also, on the phone, I enable USB Debugging, Stay Awake, and Allow Mock Locations.

Settings--> Applications --> Development --> checked all three

Using Newly-Compiled AOSP OS WITH My Hacked Kernel

(The rooting part—steps 3 & 4— should not be necessary.)

1. Compile Android 2.2 v 1.1
2. Flash complete Android 2.2 v 1.1
3. Download UniversalAndroot-1.6.2-beta.apk from computer to phone

$ adb install /path/to/Universal-Androot-1.6.2-beta.apk

4. (On the phone.) Run Universal Androot for Android 2.2 from listed apps
5. Get phone into bootloader mode: (Back on computer)

$ adb reboot-bootloader

6. Split the Android 2.2 v1.1 "boot.img" file into "boot.img-kernel" and "boot.img-ramdisk.gz".

$ ./split_bootimg.pl boot.img
Page size: 2048 (0x00000800)
Kernel size: 2206592 (0x0021ab80)
Ramdisk size: 167182 (0x00028d0e)
Second size: 0 (0x00000000)
Board name:
Command line: no_console_suspend=1 msmsdcc_sdioirq=1 wire.search_count=5
Writing boot.img-kernel ... complete.
Writing boot.img-ramdisk.gz ... complete.

6. Rename "zImage" (newly-compiled kernel) as "boot.img-kernel"

$ mv path/to/zImage other/path/to/boot.img-kernel

7. Zip up "boot.img-kernel" (formerly zImage) with "boot.img-ramdisk.gz"

./mkbootimg --kernel boot.img-kernel --ramdisk boot.img-ramdisk.gz -o my-boot.img --cmdline 'no_console_suspend=1 msmsdcc_sdioirq=1 wire.search_count=5' --base 0x20000000

8. Flash phone with new "my-boot.img" file

$ sudo ./fastboot flash boot my-boot.img

Compiling the Android OS: Take 3 -- It Works!

Last night, I followed the directions here:
http://forum.xda-developers.com/showthread.php?t=724240

I got to   ~/mydroid/$ make   and then let it compile last night. This morning, there was an error which is posted on this site: http://www.androidiani.com/forum/144139-post15.html

Basically, it was "libgps.so, not found"


The following blog post has great instructions and a fix for this error, so I followed his directions from that point on. Thank you, Al Sutton!
http://blog.alsutton.com/2010/06/29/building-aosp-for-the-nexus-one/


I flashed and rebooted the phone and it worked!

1. From the top of the source tree go to out/target/product/passion/
2. Run “sudo fastboot flash system system.img”
3. Then run “sudo fastboot flash boot boot.img”
4. Then run “sudo fastboot flash recovery recovery.img”
5. Then run “sudo fastboot flash userdata userdata.img”
6. Then run “sudo fastboot reboot”

The phone's display looks right again and it responds to the buttons again! :D I have a working compiled OS to work with now!

Compiling the Android OS: Take 2

Turns out, it's a bit more complicated than I previously thought. I ran "make clean" and then followed the instructions I've posted below. I've just run "make" again (without the -j3). I'm letting it compile for the night and tomorrow morning I will hopefully be able to finish the next steps and flash the phone successfully this time!

Thanks to lpasq at xda developers for posting the code I needed!
http://forum.xda-developers.com/showthread.php?t=724240

#clean out prior compiled files

make installclean

make clean

#update AOSP froyo source files

repo init -u git://android.git.kernel.org/platform/manifest.git -b froyo

cd ~

repo sync

#setup compiling environment and build

cd ~

. build/envsetup.sh

lunch

#USB connect N1 and initiate ADB

cd ~

adb devices

#ADB pull needed device files

cd ~

cd device

cd htc

cd passion

./extract-files.sh

#build the Passion *.img's

cd ~

make -j3

#view compiled folder's new boot.img/system.img/userdata.img

cd ~

cd out

cd target

cd product

cd passion

echo 'see flashable files:'

ls *.img

#create update.zip

cd ~

make -j3 otapackage

A Note on the Enabled Serial Port for Nexus One

It worked! Then, I flashed it to the phone and it persisted on reboot!


However, our apps could not access the newly-enabled serial port without superuser permissions. We fixed that this way.

$ ./adb shell
$ su
# chmod 777 /dev/ttyMSM0

Then, after rebooting the phone, the permissions for /dev/ttyMSM0 went back to normal (or were re-written on boot up).



For a phone running Cyanogen 6, I ran:

$ adb shell
$ su
# mount -o remount,rw /dev/block/mtdblock3 /system

I then pushed a file named 99foo to the phone's /etc/init.d/ directory (/etc/ is a symlink to /system/etc). The complete contents of 99foo:

#!/system/bin/sh
#makes USB-serial available to all users
chmod 777 /dev/ttyMSM0

I changed the permissions for 99foo so that they matched the permissions of the rest of the numbered files in this folder. I saw the existing permissions for 99foo as well as the rest of the numbered files by running this command:

# cd /etc/init.d
# ls -l

Then, I used chmod to add and take permissions as necessary. Then, I rebooted the phone. Now, the serial port is accessible to all users all the time!




For the phone running Android 2.2 with our hacked kernel, I will either edit the init.rc to allow access to /dev/ttyMSM0 for all users or, more likely, I will edit the init.rc file to run another file that I will write. Since I cannot edit init.rc while it's on the phone, I used this command (from my comPuter) to copy the init.rc to a location on my computer:

$ adb pull /init.rc /home/myname/init.rc

I will edit it. Then, I'll put it back with this command.

$ adb push /home/myname/init.rc /init.rc

I'm using this page for help.
http://www.androidenea.com/2009/08/init-process-and-initrc.html


I won't get to this very soon, as I have a more pressing matter to resolve. I'll blog more about it after I make some more progress.

Compiling the Android OS

I followed the directions on this site:
http://source.android.com/source/download.html

When I ran "make" from the "mydroid" folder, I kept getting this error:
error: gnu/stubs-64.h: No such file or directory

I'm using a 32-bit system, so I don't have a stubs-64.h. The installation guide says 64 bit systems are untested and they recommend a 32-bit system, so that seems like a strange error. Until, we did some looking around online and found out that the command they give on the installation guide points to something other than the stable froyo release (top of trunk, which I guess may be gingerbread or some updated version of froyo?).


Then, I ran this (almost the same, but I specify which version of Android OS to reference):

$ repo init -u git://android.git.kernel.org/platform/manifest.git -b android-2.2_r1.1
$ make

It compiled completely this time and now it's time to flash it to a phone!

Enabling the Serial Port on a Nexus One

The Nexus One USB port works as a serial port when there's no power coming into the connector. But the stock kernel sets it up as a console. To use it as a general-purpose serial port, you have to use a kernel with CONFIG_USB_ANDROID_ACM enabled and CONFIG_MSM_SERIAL_DEBUGGER disabled.

If you want to skip installing the NDK, downloading and compiling the kernel, you can try this precompiled zImage.

We did this on a rooted Nexus One with an unlocked bootloader running Cyanogen CM6. It's probably not necessary to be running Cyanogen for this to work.

Download NDK from here:
http://developer.android.com/sdk/ndk/index.html

Install NDK using instructions from the website.

Make sure arm-eabi-gcc is in your path. It's in android-ndk-r4b/build/prebuilt/linux-x86/arm-eabi-4.4.0/bin.

(export PATH=$PATH:/path/to/android-ndk-r4b/build/prebuilt/linux-x86/arm-eabi-4.4.0/bin to add it)

Make sure your machine has git: $ sudo apt-get install git-core

$ git clone git://android.git.kernel.org/kernel/msm.git
$ git branch -a
$ git checkout -b android-msm-2.6.32 origin/android-msm-2.6.32
$ cd msm
$ ARCH=arm CROSS_COMPILE=arm-eabi- make mahimahi_defconfig
$ ARCH=arm CROSS_COMPILE=arm-eabi- make menuconfig
Exit the menu and say "yes" when it asks if you want to save.

$ gedit .config
Turn on CONFIG_USB_ANDROID_ACM (uncomment it and change "is not set" for "=y").
Turn off CONFIG_MSM_SERIAL_DEBUGGER (comment it out)
Turn off CONFIG_MSM_FIQ_SUPPORT
$ ARCH=arm CROSS_COMPILE=arm-eabi- make

The kernel image should compile and is found in arch/arm/boot/zImage

Try kernel without permanently storing it on the phone. Download fastboot from here:
http://developer.htc.com/adp.html

Reboot into fastboot mode. Power up the Nexus One while holding the trackball. Plug in the USB cable and the fastboot screen should say "fastboot usb".

$ sudo ./fastboot boot /path/to/msm/arch/arm/boot/zImage

If you get this message, then you probably forgot to run as root.

sm/arch/arm/boot/zImage
creating boot image...
creating boot image - 2232320 bytes
< waiting for device >

Once the phone boots up, use adb shell to ls /dev/tty* and if you see dev/ttyMSM0, it worked. (We haven't tried actually using the port yet).

When you reboot you'll be back into your old kernel. Haven't flashed this for real yet.

Check out the xda-developers.com thread linked below for more info on actually using the serial port.

The following sites were helpful:
http://androidboss.com/custom-linux-kernel-for-nexus-one/
http://forum.xda-developers.com/archive/index.php/t-625434.html

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