[Galaxy Note II Original Android Development] pongster:
FAAAQ's

Kernel Frequently Asked & Answered Questions (FAAAQ)

What exactly IS the RedPill?

The RedPill is a custom kernel for the Galaxy Note 2 (N7100) International version. It's aptly named to provide users a choice. This is how I would have built Samsung's stock kernel. So, I used the Samsung Source from their site as a base and added relevant patches that are built on the shoulders of giants... such as arighi, gokhanmoral, Entropy512, AndreiLux, codeworx, netarchy, hacre, franciscofranco, Ezekeel, imoseyon, Erasmux, cattleprod, hardcore, faux123, etc. and all the kernel hackers of the world that work on making this usable for all of us... I claim nothing to be original or created by myself... I simply put together features others have created that I personally would like to see and use in my own device and share it with the world because I can AND choose to do so... While I do bugfix the occasional compile error and test for near perfection, it's nothing compared to those who write most of the code for the Linux kernel. Major props to all of them!

Where is the source for building this Kernel?

You can find the source HERE. I love GPL and We should all support Open Source Software and its Developers. Please Note that Open Source doesn't mean all of this magically wrote and patched itself... it takes a lot of FREE time to do this and would appreciate if you let us know how you've improved the code.If you know what you're doing, you can easily build your own kernel too. *Please let me know if you have any improvements you feel should be included and send me a pull request. *If it tests okay, it may be included in the next release.

FYI, I'm not particularly fond of devs who release their source as tarballs. (I'm looking at 'ya Samsung!) I'm pretty sure you use a tool like git internally to manage all the changes and revisions. Why do you have to make it so hard for those that want to play with the source by releasing it in a tarball instead of publishing it on github or bitbucket? If you're a kernel dev that does this I consider you

"open-forced" NOT "open source".

If you don't want to use git and can't be bothered with it why not make a patch and upload that instead?

Does the RedPill support ROMs for N7105 and other N7100 variants?

As of the current Revision Released, I will not be working to making it work on a device I don't currently own. I only build kernels I can actually test myself. While "building blind" might work, I prefer to break my own device before someone else's as they probably paid good money and worked hard/smart to be able to afford the device. FYI, I'm also not in favor of devs who build blindly then ask for donations so they can support the device. I want to own my device, not let it be owned by those who donated their hard earned money to get you the device. I've seen too many "devs" build blindly then ask for a donation so they can support the device, only to find a newer, better and faster device comes out and then chooses to buy that instead of the device he built blindly for and actually got donations to buy it.

Talk about Bait and Switch!

Why doesn’t the RedPill have high benchmarks?*

That’s done on purpose to keep YOU away. Seriously. The way the VM system is tweaked (dirty ratio’s, minfree values, etc.) + the focus on better latency in any type of load + a lot of other small tweaks all lead to good performance and battery drain in actual use (I like using my device and not keep it sleeping to bloat my battery stats, thank you). This

may not give you the benchmark scores you want to be able to show off

… which is good since it means YOU stay away from this kernel and continue to rely on benchmarks rather than actual usage.

Why should I even ROOT my device? Is a custom kernel more secure?

With the Exynos-Abuse Exploit out for ANYONE to use, you're probably better off rooting and installing a custom kernel that includes the fix of AndreiLux. (RedPill and Perseus as of this writing) Now I know it will void the warranty, as you all are aware of, but if the only way to secure your device and your personal data (You don't want anyone to see your google search terms and results as well as those "private" moments that you may have kept for yourself just like any normal person) is to root and install a secured kernel, what choice is Samsung giving you?

Can you imagine what a nefarious and talented malware developer could do with this? They could break your system and have a pop-up that says "Pay up to free your system from being one of my mobile drones"... OR "Donate to get the full features of your device" (This one actually happens a lot on XDA... some talented dev gives you partial features to lure you in... then WHAM, BAM, THANK YOU MA'AM... If you want the full features, please donate yada yada yada...) I digress, as always. :)

Now, would you rather wait till Samsung officially patches this exploit and run the risk of exposing yourself to the risks this exploit opens you up to? Don't assume malware devs aren't rushing their current code to try and pry their way into your system using this exploit. For all we know, they're busy trying to cover up a similar exploit and currently awaiting Play Store approval. Yes, even the Play Store Apps can compromise your system. Even if Samsung does act fast, (not as fast as AndreiLux since he fixed it in a jiffy) how sure are you that your system hasn't been compromised? You wouldn't even know it.

The best reason to root RIGHT NOW is to completely secure your system, now more than ever.

If you need to claim a warranty, you can tell them:

a. I had no choice, you messed up, xda-devs cleaned it up.

b. Flash back stock kernel and remove any trace of root and your use of a custom binary.

c. Completely brick your phone and tell Samsung that the exynos-mem exploit was actually used by malware that zapped your system dead.

I'm not a fan of any of these choices since I believe warranties should be honored by the manufacturer, especially if the bug they created was the reason for the claim for warranty in the first place.

How do I know I'm secured from the Exynos-Abuse Exploit?

Don't rely on apps that tell you whether you're vulnerable or not as the low level kernel fix AndreiLux implemented doesn't need to change the permissions of the /dev/exynos-mem.

Try running Chainfires Exploit APK and try getting the exploit to say anything else but "FAILED"... or head over to the thread HERE and download the exynos-abuse binary and run it from a terminal.

If your shell changes from $ to # then the exploit was successful, if not then you're safe.

Can the RedPill be OC'd and UV'd?

It can be UV'd and OC'd.By default, I've decided to keep all voltages and clock speeds stock as experience has taught me that NOT ALL DEVICES ARE CREATED EQUAL. You can UV the CPU arm voltages and OC using 3rd party Apps that do that. (SetCPU, VoltageControl)

Can the RedPill GPU be OC'd and UV'd?

Yes. Thanks to AndreiLux. You'll need to use STweaks to fully configure this. YMMV as always.

Why a tweaked deadline and SIO I/O scheduler?

The deadline I/O scheduler by Jens Axboe has proven itself as a low overhead, high throughput and acceptable latency I/O scheduler. *When tweaked for NAND based Mobile devices, it does even better. *While it "starves" writes by default with a 2:1 Read:Write ratio, this can easily be tuned via sysfs.

Why is my favorite governor (whichever it is) not available?

Simplicity is the Ultimate Sophistication, as Leonardo Da Vinci eloquently said. *Based on extensive testing and user feedback, we gathered that these 2 governors included gave the best performance and battery life on our device. Simple choice to have only the best ones available based on actual testing and feedback. *I included only these governors so you all have a simple choice to make in finding your favorite one. *These are all tunable via sysfs so you can skew it towards battery or performance based on what is important for you. *Don't expect uber smoothness and 16 hours screen-on time though... *there will be compromises when leaning towards any of the two factors most users consider important in a kernel.

Why LZO Compression for the Kernel?

It decompresses much faster than any other, bar none. Since the kernel size and compression speed is not an issue when using LZO in the kernel. (You only decompress the zImage when booting. Compression is done when building the kernel) Don't believe me, believe the data right HERE.

Why ARM Topology and sched_mc?*(From linaro.org)

"The sched_mc function adds a power saving awareness to the Linux scheduler which is tuned for performance by default. When sched_mc is enabled, the scheduler tries to gather the running processes in a minimal number of cpus and clusters. This choice of the location of a process is done thanks to the cpu topology function which describes the affinity between cpus."

(more info HERE)

Why is my AndroidOS usage so high?

This is most likely a reporting error from Android itself. Use Better Battery Stats to closely watch what really eats your battery. That has shown to be more reliable. (If I were Android, I'd fold buy out BBS and fold its code in by default) :) If you still have doubts, do a real world battery test, as some have done, and they saw that their battery consumption actually remained the same or in some cases even improved. YMMV, of course. Let's not fall for "placebos" here and say that "hmmmm.... since AndroidOS must be high than my battery doesn't last as long!"

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Ultimate Version FAAAQ DEPRECATED SINCE MOST FEATURES ARE FOUND ON STABLE

Why SLQB? (According to its author, Nick Piggin)* (Only for the Ultimate Revision)

”SLQB is a slab allocator that focuses on per-CPU scaling, and good performance with order-0 allocations. Fastpaths emphasis is placed on local allocaiton and freeing, but with a secondary goal of good remote freeing (freeing on another CPU from that which allocated).” Using this on the Stable version breaks ExFat from working properly. Thus, the Ultimate version is for those who don't need ExFat support.

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HyperDroidDevs FAAAQ

Where do I report Issues or Get Community Support?

Use this thread to report issues, preferably with a last_kmsg, dmesg in a text file or a logcat. How do you do those? I'll let you use XDA's brilliant search function. And no, it's not broken, the search function that is. (I've heard that so many times... "Search isn't working so I posted a question here instead...")

Where are the HyperDroidDevs and their Team from?

We are an international team of crazy people who all have real life day jobs that are mostly not related in any way to Android Development. We're crazy enough to spend sleepless nights trying to make our devices (which we all personally own and have NOT been donated) better than how we received it. We come from all over. I am from the Philippines, where it's always FUN to be! We have Devs and Team members from Spain, Greece, France, Finland, Germany, Italy, Netherlands, Canada, USA, India, Poland, Philippines and even more countries. :)

How do I show my appreciation? Can I donate to you?

You can show your appreciation concretely in several ways:

Pressing the "Thanks" Button on XDA

Follow me on Twitter @sarcastillo and "Like" our Facebook Page

Report issues politely and completely

Donating any amount is completely up to you. *I look at donations as a "tip" for a job well done, rather than a "wage" or a "bounty" to get things done. *And Tipping is always up to you... the tipper. *I won't stop development if you don't donate, that's for sure, as I do this mainly for myself and my HyperDroid mates to begin with. I make more money running my own business than this hobby so “tips” are not a necessity… it just tells me how many people actually find the work useful enough to say thank you via a financial gesture.

This Kernel will ALWAYS be FREE to Download and USE, even if the time spent making it IS NOT FREE. *That's Open Source. (The time people spend on open source projects could have been used to spend more time with their families, for example. But the Devs commitment to get something done right is almost always tugging at him to Dev just a little bit more) *:)

*I've personally donated to Devs who've done things I would never have been able to figure out at the time they did figure stuff out. *Learning anything new takes time and time, in my book, is more important than money as I can't turn back time, while I can always earn money. SO I donate to Devs who spend their free time making Stuff better and easier for those of us who haven't figured out how to get it done.