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So, I've looked at every vendor tree that I can find. Not all of them are set up the same, but that appears to be taken care of via the .mk files. I really want to help some folks with an Eris vendor tree. Is there anyone out there who can and will explain a few things to me?
1) What proprietary files can we leave in the repo, if any? I've seen at least one repo that seems to have some proprietary binaries in it, but then uses the extract-files.sh to pull the rest. I just don't get where the line is. Maybe they don't either?
2) Why can't we put all of the proprietary files in the repo? If we're building the ROM, and we're just going to put them on the ROM and post it anyway...
(I get copyright issues, but posting them in the ROM and posting them in the repo seem to be pretty much the same to me. )
Thanks!
I would like to know the same thing.
I would also like to see a detailed "map" of the files in a "generic" rom
I have tried making sense of them by looking inside, but I am having a hard time telling if the files I am seeing are generic Android, device specific, or extra files someone threw in to customize the rom
I think a good start would be a list of the minimum files required to get Android running on a device along with a description of what each file (or at least each group of files) does.
Then maybe later add a description of the optional packages.
ROM chefs could then use that list as a starting place and add the specific information for the device they are cooking for.
Anyone know of a list like this or maybe one that is at least partially complete so that we wouldn't have to start from scratch?
Dear Community,
Please read the following before starting on reading on.After lots of requests I decided its time to provide every oncoming developer with a short guide on how to start developing for our beloved Mimmi (most stuff applies also for Robyn or other Android devices).
I'd also like to get a few words passed on what actually in most cases developing is, so let's start with the basics:
There is different ways of developing there is people like Cyanogen Mod which provide you with a bunch of changes to the original Android source code which enables new features, adds hardware support or make things easier for specific device developers. However these people at Cyanogen are often not fully recognized so please make sure to thank these people as well. Besides that there are ports of similiar devices which will not be explained in this tutorial but also these developers usually put a lot of effort into their roms however since the source is already compiled changes are usually of a cosmetic nature. In this tutorial however you will find the basics on how to compile kernel or android from source in order to build your own changes into your own rom, which btw would have never been possible without the developers porting xrecovery or cwm to our devices so please give these people a big thumbs up as well after reading on.
What do I need/Environment set up
Most people have issues on setting up a the heart of your Developer Carreer, the Environment. What I strongly advise is to have at least a bit knowledge of the main usuage of Linux Distributions and also programming languages. Without these you will most likely fail at one stage or another to make a successful build.
So lets evaluate what you need :
Linux Distro (i.e. any Ubuntu should do well)
a VM or native Linux
quite a bit of Linux skills and programing skills
Time and a high tolerance of frustration
Sufficent RAM (at least 4 GB, more is advised otherwise use native Linux)
If you know how to install a native Linux Distribution you can probably skip this part, I will explain how to use a VM to fill the basic needs and keep your development area seperated from you most likely otherwise needed productive platform.
The following Steps are just keywords, if you want to develop you will need to inform yourself how to achieve all this yourself, there's lots of tutorials out there.
Step 1: Download a VM and a Linux Distro
Step 2: Install VM Software (i.e. VirtualBox or VMWare Server)
Step 3: Install the Linux Distro in VM (you'll need at least 6 GB Swap and 50 GB or More HD space to have enough room for experiments/seperate syncs/etc...)
Step 4: Figure out if you installed 32 Bit or 64 Bit (you'll need this later)
Step 5: Boot your new VM based Linux Distro
Step 6: Set up a Share Mount between your host and your VM
Step 7: download the Android Source/Cyanogen Source of your desire (i.e. : repo http://**** -b gingerbread) into a folder for you desire (the folder should represent your ROM's/Kernel name)
Building a Kernel
Building a Kernel is one of the easier parts considering the full source code is available for download. Sony Erricson Open Source Dev Website is providing fully funtional Kernel sources usually in the tar.gz format. Download the source code and extract it, or if you use a git based repository clone or checkout the project into a folder of your desire.
The next step, is not mandatory but advised to sync the entire Android repo/CyanogenRepo as the repo also provides the Cross Compiler toolchain which is needed to compile for your device.
Once everything is finished downloading you should check the following path in the Android repo : platform/linux-x86(orx64)/prebuilt/toolchain/arm-eabi-4.4.3/bin/ this is the cross compiler we will use to build the kernel itself, its vital to have the compiler present, the version number maybe different though.
Lets start with the building process itself:
Code:
cd kernelfolder
cp arch/arm/configs/semc_mimmi_defconfig .config (the command maybe change to copy another default config file, it creates a file in the root of the kernel folder called ".config"
ARCH=arm make menuconfig (this will bring up the kernel configuration menu for arm devices)
In the Menu Config you can change/add features to the Kernel once you are done safe the kernel config. Now your Kernel is ready to be compiled:
Code:
ARCH=arm CROSS_COMPILE=/pathtoandroid_source/platform/linux-x86(x64)/prebuilt/toolchain/arm-eabi-4.4.3/bin/arm-eabi- make -j4
This will start a compile with 4 Jobs using the Architecture ARM and the Cross Compiler arm-eabi from the Android Source Repo. Once finished you'll find your Image in your kernel folder under arch/arm/boot/Image. Now you'll need to build your own ramdisk this is covered here at xda as well azuzu has also build a tool available to download.
Follow the instructions to create the kernel.sin which now can be flashed with Flashtool. Changes to Kernel source will now be available to your compiled Kernel. How to change the Kernel source is beyond this tutorial but programmers in C will have fun there.
Building Android from Source
Now lets get started with the more advanced part and the most frustrating part in the beginning. The easiest way to build for the mimmi would be to sync the Cyanogen Gingerbread source code. Which can be checked out using the repo binary (see tutorials on googles website also which packages for which architecture (x86 or x64) are addionally needed also the correct java version is important)
Now lets cut to the chase.
Code:
repo sync -u http://github.com/CyanogenMod/... -b gingerbread (or froyo or another branch you would like to check out)
once your repo is synced (you could also add "-j8" to enhance the speed of the repo command, it will take quite a while) you are almost ready to start. If you synced an AOSP source you will have the get your device and hardware libraries ready first. This means you will have to port i.e. the device project and hardware project (mimmi and msm7227-common folders from CM and also hardware folder from CM) to the AOSP source. It makes sense to port these to your AOSP source since they are the most complete so far. For Camera libraries you can sync from doixanhs repo the libcamera-5mp.
Now lets get a short overview over the Android source, it contains of various folders:
frameworks
device
vendor
hardware
platform
external
These are the most interesting, frameworks folder holds a bunch of android libraries and files which provide the functionality however often you will need to change a few things here and there since the mimmi is unique in its hardware. Everything you change will need to be approved with the following command:
Code:
make update-api
This will add all the functions, variables or anything else to the current-api.xml and ensure its available at build time.
The device folder holds device specific files, build-configs and so on. Lets look at some of the important files:
Code:
device/semc/mimmi/overlay/frameworks/base/res/res/values/config.xml/power.xml
The two xmls hold configurations of the build process which are device specific either LightSensorWarmupTime and so on the full list is in the root folder of frameworks/base/res/res/values/config.xml <-- any part you feel you need to change copy the lines from there and change in you device specific config.xml.
Now to another file:
Code:
device/semc/msm7227-common/BoardConfig.mk
This files olds the device sepecific configurations for the ARM, WLAN, etc.
Look at all the files in mimmi and msm7227-common and figure out what they do, google of course will guide you on that.
Also take a look in the:
Code:
vendor/cyanogen/products/
folder and find the mimmi config and get familiar with this as well. Nobody will be able to help unless you face specific issues. Developing is learning by doing and a lot of self teaching and the will to understand all of this yourself. We can't teach but you can learn. Specific questions however are usually proudly answered by most devs if they have already figured it out.
Lets start building now, first you'll need to get your lunch command to know which devices have makefiles (I always do it to be sure)
Code:
source build/envsetup.sh
This will now add all the known devices to your lunchcombo (the devices are usually definied in the vendorsetup.sh pointing to the makefiles)
Code:
lunch
Will get you the list of available devices and will wait for user input to select the device you want to build, choose the mimmi.
Code:
make -j4
This will start the building process with 4 jobs.
Now its time to get a coffee. Usually you will have a bunch of different issues on this part but the CM source is pretty good and you might be lucky there.
Now lets look at typicial errors:
Code:
symbol not found : means a variable in used in the code has not been defined, before its use this one is a tricky one
try to locate the source file and find the line the compiler is complaining about. Now check in the framework usually in
res/res/values or layout look for the type of the erros (String or array) and look in the corresponding xml if the variable
is present. Now look in vendor/cyanogen/overlay if your variable is also declared there and so on.
Code:
function not found/function of incompatible types : also a tricky one, you might sync a repo and made local changes to
a file and suddenly your functions another file calls are not present or have changed, find the differences between them and
think about how it has changed, maybe add the function again or maybe another function does the job now. you will need
to locate the changes compare them and you should be fine again
Code:
No Rule to make target: this one is usually due to a missing/incomplete Makefile you might need to add manually or
if you don't need it anyway the easiest would be to delete the not building folder
Once your source has finished compiling you will find you system image in:
Code:
out/products/mimmi/system/
As of now unfortunately its still missing a few files here and there. Compare ROMs and Compare what might needs to be added. However I advise not switch libraries around its best to use your own libraries. However sometimes you will face issues when doing this so start with the files created there and just add the recovery and ramdisk to your rom. Now observe via adb if everything is running. This will take time and add one missing lib after another one and reboot, after each (like grallocs or librils or fm libs and so). This is basically a debugging part of the job.
You will now add one by one more functionality, but keep in mind to use logcat to see what goes wrong, maybe some stuff can be changed in the source rather then randomly adding stuff.
also this one just in case.
Hey there c: As always, you come surprising everyone with your stuff haha Good job on this one, I think it is always good to have some tutorials from the people who build specifically for our Mimmi's
Before reading this, I wanted to get started on developing and I went to Android's official developers site, I did some steps, now I have the complete source of Android here (I use Ubuntu 10.04, the LTS version... Dunno if telling you that it is LTS ver. really matters, but just in case) andthe whole environment ready to build. Now, reading at this, I realize I don't have 4Gb of RAM on this "old" (2007..) notebook. Anyways, the thing is: I followed the steps listed here, but when I wrote this command-
Code:
$ make -j4
-the terminal started to execute files, or something... I'll add a screenshot at the end about this. It has been 3 days since that, and the terminal is still doing the same. I know developing requires a lot of patience, but... 3 days? Is this normal?? I have looked through the Internet for problems with this command, but no one seems to have talked about it.
Thanks for your time, work and effort for the community, we really appreciate it c: Bye!
Link to the Screenshot:
http://i259.photobucket.com/albums/hh313/link_4ever/Screenshot.png
The 'make -j4' uses 4 threads to compile everything, if your notebook does not have at least an hyperthreading-technology enabled CPU, well, that's to expect when building an entire OS, plus you don't have sufficient RAM, I do have 2GB and a DualCore CPU and it takes at least 1 hour to compile an average desktop kernel with that same command. I have not tried to compile android, but I think that it will take at least 4 hours to compile everything. Just my thought.
RozenTensai said:
The 'make -j4' uses 4 threads to compile everything, if your notebook does not have at least an hyperthreading-technology enabled CPU, well, that's to expect when building an entire OS, plus you don't have sufficient RAM, I do have 2GB and a DualCore CPU and it takes at least 1 hour to compile an average desktop kernel with that same command. I have not tried to compile android, but I think that it will take at least 4 hours to compile everything. Just my thought.
Click to expand...
Click to collapse
Thank you for your answer! Just ten minutes ago, the 'make' command finished ! And about my notebook, it is just like yours: 2Gb RAM and Dual-Core CPU, I'm not sure but I think it runs at 2,8 GHz. And also, like I said earlier, I know developing takes time. I know how slow processes can be, in fact, there were commands previously that took 1 hour or more to finish their tasks. 1 hour, 4 hours, it's ok but... 3 days? Isn't it a bit too much xd?? Now I'm afraid to turn off the computer because I don't want to compile that thing again hahaha
the "-j" option depends on the number of (virtual) cores you have.
get the number:
Code:
grep processor /proc/cpuinfo | wc -l
if you have native linux and like to work on the machine I recommend do lower the number at least -1 otherwise get a coffee and keep hands off the build process
b
make -j4, lol. Many people do not have. 4 cores on the processor
paul-xxx said:
make -j4, lol. Many people do not have. 4 cores on the processor
Click to expand...
Click to collapse
This parameter refers to threads instead of hardware cores
Sp4rrow said:
This parameter refers to threads instead of hardware cores
Click to expand...
Click to collapse
ok. probably a mistake. but still. I always use 2. it brought to me the best results
I use j6
And also j refers to jobs everybody may change to what they want. For kernel i build with j12.
If you know better like it seems you always do write it down.
Sent from my U20i using xda premium
I can't find any 2.1.1.A.0.6 Sources. Link to the sources you use slade?
http://developer.sonyericsson.com/cws/devworld/search-downloads/opensource?cc=gb&lc=en
should be:
x10_x10mini_X10minipro_x8_eclair_2.1.A.0.435.tar.gz
Stock Kernel with only CWM5 installed...
Slade i want some help from you. how can i embed CWM5 in the stock kernel without any other changes to it??
i want a stock kernel with nothing changed in it only CWM5 installed in it. how this can be done???
i forgot to say the most important thing!: Thank you very much for your work and effort Slade
I just came to the configuration menu of the kernel. i see there are options predefined for the mimmi, but how can i optimize it more, there are soooo many options, and to tell the truth i don't have a clue what they do
I just went through the process of compiling a custom ROM and they used a stock kernel. I would like to incorporate a different kernel when I compile and instead of the stock. I know I could compile them separately and have them flash together but I want one zip to flash. Just would like to go through the process to learn.
Any help on how to do this or what I have to do when compiling?'
Thanks.
MAXGEN said:
I just went through the process of compiling a custom ROM and they used a stock kernel. I would like to incorporate a different kernel when I compile and instead of the stock. I know I could compile them separately and have them flash together but I want one zip to flash. Just would like to go through the process to learn.
Any help on how to do this or what I have to do when compiling?'
Thanks.
Click to expand...
Click to collapse
One of the easiest ways of doing this would be to take the boot.img thats contains the custom kernel you want and deleting the stock boot.img containing the stock kernel in your .zip file and replacing that with the boot.img of the custom kernel. Essentially you are just swapping the boot.img file in the .zip files with the one containing the custom kernel rather then the stock kernel. Let me know if you need me to explain things further or have any other questions I'll be happy to help you out.
shimp208 said:
One of the easiest ways of doing this would be to take the boot.img thats contains the custom kernel you want and deleting the stock boot.img containing the stock kernel in your .zip file and replacing that with the boot.img of the custom kernel. Essentially you are just swapping the boot.img file in the .zip files with the one containing the custom kernel rather then the stock kernel. Let me know if you need me to explain things further or have any other questions I'll be happy to help you out.
Click to expand...
Click to collapse
Thanks for the response.
I have to first compile the custom kernel then it seems like an easy process after that. I'm going to try to compile Franco kernel for nexus 5 if u heard of it. Its been pretty good for me.
Any tips for compiling another project or Franco kernel would be great!? I will make a separate folder for that kernel git project and compile it there.
I also want to use tool chain like Linaro and maybe Sabermod but those are for nexus 4, maybe I can port it over.
MAXGEN said:
Thanks for the response.
I have to first compile the custom kernel then it seems like an easy process after that. I'm going to try to compile Franco kernel for nexus 5 if u heard of it. Its been pretty good for me.
Any tips for compiling another project or Franco kernel would be great!? I will make a separate folder for that kernel git project and compile it there.
I also want to use tool chain like Linaro and maybe Sabermod but those are for nexus 4, maybe I can port it over.
Click to expand...
Click to collapse
Franco kernel is an excellent kernel can't really go wrong with it. On your other note, Linaro is not Android device specific it can be used to compile kernels for a plethora of devices, I would recommend taking a look at this great guide on how to use Linaro to compile your kernel and how to customize the Linaro toolchain to suit your needs.
shimp208 said:
Franco kernel is an excellent kernel can't really go wrong with it. On your other note, Linaro is not Android device specific it can be used to compile kernels for a plethora of devices, I would recommend taking a look at this great guide on how to use Linaro to compile your kernel and how to customize the Linaro toolchain to suit your needs.
Click to expand...
Click to collapse
So I tried following the post. Just not sure about a lot of things and got confused and couldn't compile.
So what I'm trying first before I use the LInaro tool chain is to try to compile the Franco kernel without it. I clone Franco hammerhead git and link the arm-eabi-4.6 toolkit
make hammerhead_defconf
make -j7
Seem to compile with no errors, took a minute though which seems quick but not sure where it exported to.
Tried looking in the arch/arm/boot/ but no look.
I want compile a boot.img as well.
MAXGEN said:
So I tried following the post. Just not sure about a lot of things and got confused and couldn't compile.
So what I'm trying first before I use the LInaro tool chain is to try to compile the Franco kernel without it. I clone Franco hammerhead git and link the arm-eabi-4.6 toolkit
make hammerhead_defconf
make -j7
Seem to compile with no errors, took a minute though which seems quick but not sure where it exported to.
Tried looking in the arch/arm/boot/ but no look.
I want compile a boot.img as well.
Click to expand...
Click to collapse
I would recommend trying the following procedure:
Code:
mkdir franco
cd franco
git clone https://github.com/franciscofranco/hammerhead.git
After the clone operation completes rename the cloned folder to hammerhead or make sure it named hammerhead.
Now make sure your are in the franco folder you created and run the following commands:
Code:
git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.6
export PATH=$(pwd)/arm-eabi-4.6/bin:$PATH
export ARCH=arm
export SUBARCH=arm
export CROSS_COMPILE=arm-eabi-
cd hammerhead
make hammerhead_defconfig
make -j4
Once it finishes this you should now have a zimage outputted in the path arch/arm/boot/zImage. To make the process of putting your zimage and module together run the following commands:
Code:
mkdir ~/franco/kernel_output
cp ~/franco/hammerhead/arch/arm/boot/zImage ~/franco/kernel_output/zImage
find ~/franco/hammerhead -name "*.ko" -exec cp {} ~/franco/kernel_output \; (You may have to run the command without the ";")
You should now have everything you need to make a boot.img. Let me know how it goes and if you still have questions.
Thanks for your help, W-XC (curious what that means and you have flying shoe is it because you run? You running in the next Boston Marathon?)
The kernel is actually using 4.7 so I just used the right git. I also found out it wasn't compiling because there was any error in that specific driver for CPU governor. The dev actually was about to push a fix and supposedly it will be push tomorrow but shared the commit so I was able to make the fix manually. Either case it compiles now. Working on step 2 which is to compile into the ROM.
I was curious you seem to know your stuff. Are you kernel dev? How did you gain your knowledge? I wanna learn more about Android OS and linux kernel? I taken basic OS classes in college so a lot of introduction to concepts but nothing on coding it though. Any books or anything you can recommend on any of these areas or anything closely related worth knowing? Thanks again.
For making a boot.img I tried the following. What would you suggest for mkbootimg?
I used this script to get my ramdisk.
http://www.enck.org/tools.html
But I'm little confused on where do you get the script for mkbootimg?
Is it from the android source or is it generated when you build the kernel or is it some script that someone made?
I found this posting for building a kernel with mkbootimg but the dilemmaI"m no having is what is correct commands for building.
http://www.droidforums.net/forum/rescue-squad-guides/31452-how-compile-your-own-kernel.html
The dev mention some commands in a posting several months ago.
http://forum.xda-developers.com/showpost.php?p=47167725&postcount=291
That might be a way to go but the argument doesn't take with the mkbootimg from the droid forums. Syntax is not right so it makes me think that mkbootimg is unique.
MAXGEN said:
Thanks for your help, W-XC (curious what that means and you have flying shoe is it because you run? You running in the next Boston Marathon?)
The kernel is actually using 4.7 so I just used the right git. I also found out it wasn't compiling because there was any error in that specific driver for CPU governor. The dev actually was about to push a fix and supposedly it will be push tomorrow but shared the commit so I was able to make the fix manually. Either case it compiles now. Working on step 2 which is to compile into the ROM.
I was curious you seem to know your stuff. Are you kernel dev? How did you gain your knowledge? I wanna learn more about Android OS and linux kernel? I taken basic OS classes in college so a lot of introduction to concepts but nothing on coding it though. Any books or anything you can recommend on any of these areas or anything closely related worth knowing? Thanks again.
Click to expand...
Click to collapse
MAXGEN said:
For making a boot.img I tried the following. What would you suggest for mkbootimg?
I used this script to get my ramdisk.
http://www.enck.org/tools.html
But I'm little confused on where do you get the script for mkbootimg?
Is it from the android source or is it generated when you build the kernel or is it some script that someone made?
I found this posting for building a kernel with mkbootimg but the dilemmaI"m no having is what is correct commands for building.
http://www.droidforums.net/forum/rescue-squad-guides/31452-how-compile-your-own-kernel.html
The dev mention some commands in a posting several months ago.
http://forum.xda-developers.com/showpost.php?p=47167725&postcount=291
That might be a way to go but the argument doesn't take with the mkbootimg from the droid forums. Syntax is not right so it makes me think that mkbootimg is unique.
Click to expand...
Click to collapse
The W-XC in my avatar stands for Watertown Cross-Country which is the team I used to run on and the flying shoe with the track wings represents our track team, as I love to run I thought it was a fitting avatar. As far as running the Boston marathon I am not running this year but I would love to someday, I am unfortunately not in good enough form to run a marathon right now due to a prolonged battle with an injury I sustained last spring, but I'll keep training and keeping running!
I'm glad you were able to make the fix on the kernel, often times errors that seem to pop out of nowhere are related to fixes not being pushed to the repository you were syncing and using to build at the time. Thank you for the nice compliment it is greatly appreciated, I am not a kernel developer just an overall aspiring developer who loves everything Android related and trying to contribute and help others however I can. I would say 99% of my knowledge of everything Android related has come from XDA and hours upon hours of Googling things related to kernel development, reading about something not understanding something then Googling the parts I didn't understand, piecing together things then Googling more things to help me understand, after a while you slowly start putting the pieces of knowledge together as you learn more and then you still keep learning. For resources on learning kernel development I would recommend learning the C programming language as it is the building block of kernel development. A great resource for learning C is the free online e-book Learn C The Hard Way. Another critical element of understanding Android kernel development is the Linux Kernel and it's drivers which is why I would recommend taking a look at Linux Device Driver's Third Edition, while parts of it are outdated the fundamental concepts are still very much applicable. As far as pure Android Kernel aspects and Linux Kernel aspects go the free-electrons group has some invaluable presentations that cover these subjects as well as other critical areas of embedded development that relate to kernels.
For the mkbootimg binary I would recommend downloading these unpack, repack, ramdisk tools. They have proven invaluable for me when working with img files and kernels. Download the scripts and binaries and put them in your ~/bin folder and make sure to give them the proper permissions that way they will be in your path and you can use them properly. Once you have them installed I would recommend obtaining a copy of the Nexus 5's latest boot.img (The factory images Google Provides should have it in the images .zip file included in the factory image). After doing that decompile the stock boot.img file using the umkbootimg binary, this should present you with an output of a ramdisk and a zimage. Next, take the zimage you compiled with the franco kernel source and replace the stock boot.img zimage with the zimage you compiled from franco kernel. Then run the mkbootimg binary with command (In terminal it should give you the command to easily re-pack the boot.img) to re-pack your new boot.img. The output of the new boot.img will have the default name new_boot.img or similar name. Re-name this file to boot.img and delete the old boot.img from your .zip file of your ROM and swap in the boot.img file you just created. You have now included the custom kernel you wanted in your ROM.
As always let me know if you still have questions I'll be happy to answer them :good:.
Thank you so much!!! Probably going to have to take some time to digest everything but definitely will have more questions when I'm done.
Quick question, do you have see "C" being replace? I have read some C code but haven't not yet coded anything in C. I been told that low level access you get with C is not comparable with other languages. I guess you would have to go to ASM to get even more access. ASM personally I run from it, probably should do more of it for practice. We do a lot of high level language C++, java, python and some others in school but no C. I probably can't avoid not being comfortable in it? C is not going to be replace by anything in future??
MAXGEN said:
Thank you so much!!! Probably going to have to take some time to digest everything but definitely will have more questions when I'm done.
Quick question, do you have see "C" being replace? I have read some C code but haven't not yet coded anything in C. I been told that low level access you get with C is not comparable with other languages. I guess you would have to go to ASM to get even more access. ASM personally I run from it, probably should do more of it for practice. We do a lot of high level language C++, java, python and some others in school but no C. I probably can't avoid not being comfortable in it? C is not going to be replace by anything in future??
Click to expand...
Click to collapse
You are correct in that to get even more low level access you start getting into assembly territory. What makes assembly difficult and what makes people from run form it is unlike very high level languages such as Python, Java, etc. it is much less human readable and a lot closer to machine language (Binary code), however like anything practice makes perfect the more you practice with a language the easier things get and the more confidence you have in programming things with it. If you really want to customize and develop kernels C is a must there is no getting around that unfortunately. As far as C being replaced with anything in the future, will it ever be replaced, probably as is the case with technology, but as far as it being replaced with anything equivalent or better in the next 10-20 years I doubt it, as it would take years to develop a new standard and even longer to be adopted and standardized to the point C is used and accepted today.
Hi,
I'm currently in the process of developing a project for my University course wherein I will be hopefully editing the functionality of the HCE Feature of Android to allow me to set my own UID when emulating a card.
Now, i've downloaded the AOSP source, and built a custom image with no edited code and installed that to my Nexus 7 (This includes downloading and including the Vendor specific hardware drivers), and i'm stuck on the next part.
I physically cannot find the device code that governs the NFC features of Android, and i'm unsure how to go about a) Looking for it, and b) How I should be editing this code.
Is the code for NFC in Android in the base Kernel? and if so how would I edit that before I run "make" again and hope it builds? or is it elsewhere? I've noticed that the files in the Vendor folder i've downloaded and extracted are in a .ncd format, which I don't think is editable.
Any help I can get on this would be greatly appreciated.
Hello,
I'm willing to try and build a custom rom, but I've been diving through the site for a few days and I still don't get it. I believe I do have the required background to do this: programming, linux, etc. and I have wide experience as a phone user, etc. It's just that either I'm not reading what I need or the way I want it. The problem, I believe, is that all I find are guides telling me to install this and those tools and then open this and that and voila! you got your rom. But they're not explaining WHAT exactly goes into those roms, or what is expected to go there, what's the purpose of those contents, etc., and I can't really catch with that. I feel at a loss and hate wasting my time turning around for nothing.
1. I don't understand the difference between a flashable rom and one that is meant to be installed through recovery, although I can see they're different. Do they both models contain the same kind of data? Is there any restriction to what one model can contain over the other one? If so, how would I convert from one to the other? But please, don't tell me to use this or that tool. I just need the theory behind it. Something of sorts like: "You need to extract this or that from this tarball, then mount this image, then the directory tree there goes in that directory over the other model of rom"
2. update-binary: Okay I guess this is run when installing from recovery, and this takes care of installing the rom, right?wrong?. Is this a per-rom thing, per-device thing? generic? If it's per-rom, how to generate it? do I need to compile something? Is there any generic source code that can be used as a start?
3. Although I have a basic understanding of how the Linux directory tree works, I know Android works on top of a heavily modified Linux. So can you explain briefly how the directory tree works? For instance, I believe /data/data is where Android apps install to, in /system/bin or xbin I can find busybox binaries/symlinks if present. /dev and /proc look the same as in Linux. I don't know about /sys. Also how are both rom models deployed to this tree? What is basically being copied?
4. If I were to compile a kernel, where do I find the Android kernel sources? or is it just a generic Linux kernel? where can i get a basic config for the device? Last time I checked my device hadn't /proc/config.gz but maybe I could get it from another rom with it enabled or something. What toolchain and where to get it? Oh and if you know of a native arm version of gcc or whatsnot, I'd prefer that. Setting up IDEs or toolchains is a nightmare. I don't like crosscompiling. But crosscompiling or not, a directory with all needed binaries without needing to set up system variables nor other stuff, would be amazing.
I surely have a lot more questions that I can't get from the back of my mind now, and I'll have yet more as you explain. But the point of my questions was mainly trying to explain the degree of the loss I'm at, so you can assist me better.
If it looks like a foolish petition, well, that's because I'm quite stubborn and can't catch things that don't go my way. I really need to understand the basics before I can move into actually doing something. I want to build a rom for the right reasons(to me). It's not just about packing a set of apps or themes with it, but about learning and doing other stuff like trying to fix things that are not supposed to work for the device in that Android version, etc.
If you can't help, congrats for reading through here anyways But any help is greatly appreciated :good:
oxiroxt said:
Hello,
I'm willing to try and build a custom rom, but I've been diving through the site for a few days and I still don't get it. I believe I do have the required background to do this: programming, linux, etc. and I have wide experience as a phone user, etc. It's just that either I'm not reading what I need or the way I want it. The problem, I believe, is that all I find are guides telling me to install this and those tools and then open this and that and voila! you got your rom. But they're not explaining WHAT exactly goes into those roms, or what is expected to go there, what's the purpose of those contents, etc., and I can't really catch with that. I feel at a loss and hate wasting my time turning around for nothing.
1. I don't understand the difference between a flashable rom and one that is meant to be installed through recovery, although I can see they're different. Do they both models contain the same kind of data? Is there any restriction to what one model can contain over the other one? If so, how would I convert from one to the other? But please, don't tell me to use this or that tool. I just need the theory behind it. Something of sorts like: "You need to extract this or that from this tarball, then mount this image, then the directory tree there goes in that directory over the other model of rom"
2. update-binary: Okay I guess this is run when installing from recovery, and this takes care of installing the rom, right?wrong?. Is this a per-rom thing, per-device thing? generic? If it's per-rom, how to generate it? do I need to compile something? Is there any generic source code that can be used as a start?
3. Although I have a basic understanding of how the Linux directory tree works, I know Android works on top of a heavily modified Linux. So can you explain briefly how the directory tree works? For instance, I believe /data/data is where Android apps install to, in /system/bin or xbin I can find busybox binaries/symlinks if present. /dev and /proc look the same as in Linux. I don't know about /sys. Also how are both rom models deployed to this tree? What is basically being copied?
4. If I were to compile a kernel, where do I find the Android kernel sources? or is it just a generic Linux kernel? where can i get a basic config for the device? Last time I checked my device hadn't /proc/config.gz but maybe I could get it from another rom with it enabled or something. What toolchain and where to get it? Oh and if you know of a native arm version of gcc or whatsnot, I'd prefer that. Setting up IDEs or toolchains is a nightmare. I don't like crosscompiling. But crosscompiling or not, a directory with all needed binaries without needing to set up system variables nor other stuff, would be amazing.
I surely have a lot more questions that I can't get from the back of my mind now, and I'll have yet more as you explain. But the point of my questions was mainly trying to explain the degree of the loss I'm at, so you can assist me better.
If it looks like a foolish petition, well, that's because I'm quite stubborn and can't catch things that don't go my way. I really need to understand the basics before I can move into actually doing something. I want to build a rom for the right reasons(to me). It's not just about packing a set of apps or themes with it, but about learning and doing other stuff like trying to fix things that are not supposed to work for the device in that Android version, etc.
If you can't help, congrats for reading through here anyways But any help is greatly appreciated :good:
Click to expand...
Click to collapse
I am not terribly knowledgeable about all of this, but I will take a crack at it. Others can feel free to correct me.
1. "Flashing" is usually done through the recovery from a zip with an update script inside. That script is in a language called "edify". Read more about Edify Here and Here.
The only other common way that I know of installing a ROM is through fastboot in the bootloader, but that is normally only used with official factory images. Also, I think Samsung ROMs are often flashed with a proprietary program called Odin.
2. I think that the update-binary is standard across all recent devices. I think it is just an interpreter for the Edify scripting language. Old versions of android used a somewhat different scripting language and required a different file. You can probably pull the binary out of another recent zip and use that. The main thing you have to worry about is the update script (instructions for what the zip does) and the folder structure of the zip.
3. I am not confident to explain much here, but the apps and their data are stored in different places. User apps are stored in /data/app with app data stored in /data/data, I think. System apps are installed in /system/app. There is more files stored on the "sdcard" partition which can be internal or external, depending on the device.
4. Kernel sources are usually provided in the source code from whatever repo you are using. Different ROMs use different bases. Here is some info about grabbing the AOSP kernel sources with git: http://source.android.com/source/building-kernels.html
Many of the more popular ROMS have specific build instructions on their individual github pages (Cyanogen, Paranoid Android, etc), so you might what to look at those, too. Also, depending on the individual devices, there might be proprietary binaries sourced from the device or hardware manufacturers for things like camera drivers, graphics chips, etc.
If you want a walk through of the basic build process google has a tutorial. The last time I checked there seemed to be some outdated info, but it might give you a general idea of the build process. http://source.android.com/source/initializing.html
Hopefully someone more knowledgeable can give you more info, but that is all I got
synesthete said:
I am not terribly knowledgeable about all of this, but I will take a crack at it. Others can feel free to correct me.
1. "Flashing" is usually done through the recovery from a zip with an update script inside. That script is in a language called "edify". Read more about Edify Here and Here.
The only other common way that I know of installing a ROM is through fastboot in the bootloader, but that is normally only used with official factory images. Also, I think Samsung ROMs are often flashed with a proprietary program called Odin.
2. I think that the update-binary is standard across all recent devices. I think it is just an interpreter for the Edify scripting language. Old versions of android used a somewhat different scripting language and required a different file. You can probably pull the binary out of another recent zip and use that. The main thing you have to worry about is the update script (instructions for what the zip does) and the folder structure of the zip.
3. I am not confident to explain much here, but the apps and their data are stored in different places. User apps are stored in /data/app with app data stored in /data/data, I think. System apps are installed in /system/app. There is more files stored on the "sdcard" partition which can be internal or external, depending on the device.
4. Kernel sources are usually provided in the source code from whatever repo you are using. Different ROMs use different bases. Here is some info about grabbing the AOSP kernel sources with git: http://source.android.com/source/building-kernels.html
Many of the more popular ROMS have specific build instructions on their individual github pages (Cyanogen, Paranoid Android, etc), so you might what to look at those, too. Also, depending on the individual devices, there might be proprietary binaries sourced from the device or hardware manufacturers for things like camera drivers, graphics chips, etc.
If you want a walk through of the basic build process google has a tutorial. The last time I checked there seemed to be some outdated info, but it might give you a general idea of the build process. http://source.android.com/source/initializing.html
Hopefully someone more knowledgeable can give you more info, but that is all I got
Click to expand...
Click to collapse
OMG Finally some light! THANK YOU, THANK YOU, THANK YOU for all the info. I didn't get much right now, I'll need to read through your post a few times before I get it all, haha. I'll be sure to check the links too. Thank you!