Samsung Galaxy S5
Why CyanogenMod?

I was asked, why did you put a beta version of CyanogenMod on your pocket computer, with bugs, rather than sticking with the carrier's image, where everything works (sic) and which is optimized (sic) for their network?

(This page was written for the Samsung Galaxy S3 on Verizon, which has a locked bootloader. It was updated for the Galaxy S5, with an unlocked bootloader. But salient points about Verizon and its image have been retained.)

What's Wrong with the Carrier's Android Version?

My carrier is Verizon, but these complaints are made, with varying details, by forum posters about every carrier's version of Android. A common theme is, I want to do things with my pocket computer way beyond the cellphone role, and the carrier does not intend to support such usage.

• The very first thing I discovered about Verizon's OS was that I can only deposit files on the machine using protocols provided by the carrier, in places defined by the carrier, and with content-types approved by the carrier. This means photos, video (movies) and music. I could not send my SSH and X.509 credentials, my web materials, or my backups from the phone that's being upgraded. This is a showstopper.

• My backup procedure involves connecting by SSH from the backup server to the host to be backed up and using rsync to copy the relevant files. Therefore I need to install a SSH server (Dropbear), which is impossible without root access. This is a showstopper.

• Carriers rarely update their OS image to the latest version, and they never issue security patches. This commentary was written for the Galaxy S3, which was getting Android 4.1.x Jelly Bean. At that time about 60% of Apple iDevices had upgraded to IOS-6, while about 2% of Android devices were on Jelly Bean, the upgrade campaigns having been started at about the same time. The lack of updates is a showstopper.

  However, if you have an unlocked phone running the manufacturer's image, Samsung at least is a lot better at sending out patched images.

• Verizon's OS includes a lot of software, commonly referred to as crapware, for paying for media in their walled garden such as ringtones, music, and special apps. I never use Verizon's store, nor do I ever use media from any source in the categories offered, but these apps cannot be uninstalled. This is not a showstopper but is a very annoying territory violation on my pocket computer. While I have plenty of flash memory, Verizon's system image occupies 820Mb whereas CyanogenMod plus Google Apps occupy 245Mb (both compressed; about 1.5:1 compression). I would very much like to get this garbage off my machine.

• Carriers and manufacturers improve the Android user interface. For example, on the Droid-3 stock image the ambient light sensor affected the brightness of the screen, but could only make it brighter, not dimmer, a disaster for battery life. (I didn't actually check if this misfeature continues to Verizon's OS image for the Galaxy S III.) Currently there are complaints that HTC's images have a draconian task kill policy, so multitasking is useless unless you override the policy in the developer options. I would prefer to do without carrier improvements to the Android OS.

• Carriers have their idea of how people ought to use their cellphones, typically involving a lot of interaction with social media servers that takes correspondingly much data traffic, CPU time, and battery energy. I don't want to be dragged into this kind of usage, and other forum posters complain about slowness getting work done, and poor battery life, due to this kind of wastage.

What About Rooting the Stock OS?

Some of my issues could be solved if I would jailbreak the carrier's OS by installing the su (superuser) application. But Verizon has a locked bootloader, which must be broken before a user can take control of his pocket computer. Then I would need to undo a lot of the modifications that Verizon made to Android. It seems more prudent and more economical to put on the machine an up-to-date OS image intended for developers and root users, rather than trying to straighten out Verizon's back-version OS.

What's Good About CyanogenMod?

• AOSP (Android Open Source Project) is the basic community of Android, and publishes the source code for carriers to port to their devices.

• The basic goal of CyanogenMod is to put an AOSP OS on the phone, with the necessary tweaks to get it to run on the various vendors' equipment, and with a subset of features and enhancements not normally present in AOSP and in carriers' ports of AOSP to their devices.

• While I would much rather run a CyanogenMod image qualified as stable, as of 2015-04-15 CyanogenMod-12 based on Android-5.0 Lollipop is only available as nightly builds (for all supported devices).

• CyanogenMod is intrinsically rooted.

• Using root access, I can install the Dropbear SSH server, and using this server (plus rsync for Android) I can do my normal backups.

• CyanogenMod has a normal permission policy for the SD cards, so that I can put the files I need onto the pocket computer either with SSH or with ADB.

• Verizon crapware and its supporting files are of course not present in CyanogenMod. Neither are Verizon branding and improvements.

• Interaction with off-site cloud services is chosen and controlled by me, not by my carrier.

• Device performance has beeen excellent, including long battery life.

Conclusion

The carrier's version of Android prevents me from doing important activities on my pocket computer; CyanogenMod enables those activities. Therefore I have broken the locked bootloader and have installed CyanogenMod on my device.

Appendix: History of Android and AOSP

Here is a summary of the history and provenance of Android, extracted from this Wikipedia article about AOSP.

• Android Inc. was founded in 2003-10-xx by four senior executives who had founded or been highly placed in other tech companies.

• On 2005-08-17 Google purchased Android Inc., keeping the founders.

• On 2007-11-05 the Open Handset Alliance was created, a consortium of tech companies, handset manufacturers, carriers, and chipset makers, led by Google. Android was its first (and only?) product.

• At some time, the Android Open Source Project was created and funded by Google, with the purpose of maintaining Android and publishing it in open source form. AOSP also publishes the Android Compatibility Guide, which defines the requirements for a branded port of Android to specific hardware to call itself Android. Noncompliant ports do not get access to the Android Market (Play Store).

• On 2008-10-22 the HTC Dream (G1 on T-Mobile) was released, running Android, and sponsored by Google.

• After that, Android went viral.