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Hello.
I am wondering about the distinct difference between updating Android devices (I have a Samsung Captivate) vs how it is done in linux. It has been a couple of years since my lat linux box, but the process was distinctly different. Specifically, we could get the source to the kernels and all of the modules that we wanted and compile them for added capabilities. Moreover, the file system (data, apps, etc) were all separated from the /boot partition. If a kernel didn't work, it was no problem to boot into the older kernal and try and fix the new one. Never did we have to destroy all of our data to try new kernels, modules, etc.
Why is this so different for Android? Specifically, why do we have to reflash the whole ROM destroying everything else in the process? Is there another way to do this that I am missing or what is the difference that causes this to be necessary?
Thanks so much for the feedback...
would also like to know this one..
Ok, following up on the original inquiry...
Samsung has dropped the 2.2 source for the Galaxy S. Should this source be configurable for any of the Galaxies (i.e. Captivate?) or do we need to wait for specific Captivate source? Also, can the kernel be recompiled and replaced by itself or does the whole ROM need to be flashed? I'm still confised to why this process seems so much more limited than the typical linux cycle...
If i flash a Bad Kernel and my Phone dont boot. ( HTC Desire)
I can flash the old Kernel and it will boot again No need for ROM reflash....
I've got an HTC legend 2.1 stock Rom from virgin mobile.
Now I'm somewhat new to Android. I've been reading up a lot about rooting and custom roms but I'm kind of in-wanting to do this due to bricking possibilities. From my understanding, to "root" the legend, you would need a goldcard and some programs that run through the debug enabled. Isn't it a Linus type kernel? Couldn't someone build an app or program that can do everything in a click? I mean, people have found ways to temp. Root..and what I see Is that you run a program on the pc after having the goldcard which then roots it. But what if you put the "external" parts into the app.its Linux,and if you have root access then you should just be able to slip in the extra work during the other processes.
I'm I wrong? Isn't it just possible?
If I had the knowledge, is work on this myself....I only understand a little java...
Hi Fellow old and New Devs,
The title suggests it all. I have four questions that I think ALL newbies want to understand. I would try and explain them, but as I am just coming out of the newbie stage, I'm sure people would prefer an answer from a experianced Dev.
When answering a question please put the Question Number. Feel free to answer only one or two of the questions, I'm sure other people will cover your missing fields of knowledge.
Here they are:
1. What is rooting? Can I root my device (HTC Buzz Wildfire) and keep the stock interface? Will I loose my data?
2. What do all these Dev's mean by Recovery? What are they, why are they needed?
3. What is a ROM? Do I need to be rooted for a custom ROM? How can you trust them? Will I loose my data when installing a custom ROM?
4. What is a Kernal? How are they Different to ROM's? Should I change from the stock Kernal?
I know this is a tall order and you could write a book on the topic, but please could you write a short (a couple of sentaces will do) paragraph on each question you choose to do.
When we get enough understandable answers I will edit this post publish the Final answers for other newbies in the future.
Also feel free to enter the poll! As this is a Dev site I presume one of the options will have the most votes but we will see....
Cheers for any contribution in advanced.
th3ant
th3ant said:
Hi Fellow old and New Devs,
The title suggests it all. I have four questions that I think ALL newbies want to understand. I would try and explain them, but as I am just coming out of the newbie stage, I'm sure people would prefer an answer from a experianced Dev.
When answering a question please put the Question Number. Feel free to answer only one or two of the questions, I'm sure other people will cover your missing fields of knowledge.
Here they are:
1. What is rooting? Can I root my device (HTC Buzz Wildfire) and keep the stock interface? Will I loose my data?
2. What do all these Dev's mean by Recovery? What are they, why are they needed?
3. What is a ROM? Do I need to be rooted for a custom ROM? How can you trust them? Will I loose my data when installing a custom ROM?
4. What is a Kernal? How are they Different to ROM's? Should I change from the stock Kernal?
I know this is a tall order and you could write a book on the topic, but please could you write a short (a couple of sentaces will do) paragraph on each question you choose to do.
When we get enough understandable answers I will edit this post publish the Final answers for other newbies in the future.
Also feel free to enter the poll! As this is a Dev site I presume one of the options will have the most votes but we will see....
Cheers for any contribution in advanced.
th3ant
Click to expand...
Click to collapse
Okay, from the best of my understanding, here we go:
1: Rooting. To understand this, we must consider a computer, running linux, windows, or mac. In windows, the "Administrator" account is similar to the root account in linux and mac. Basically if you have root privileges in a system, you can modify every part of the filesystem, as well as perform any tasks the system is equipped to handle. Basically achieving root on an android device means that you can unlock the ability to flash roms, mod, and otherwise hack your device any which way you like. Nearly every model of android device has been rooted, so in most cases, yes you can root XXXXX phone. Also, since you're just gaining privileges, you can root without losing any data, apps, or settings.
2: Recovery. This is a long standing concept in SoC/Embedded device hacking. Basically it is a minimal operating system that performs some very basic, but very important tasks. The reason for it is so that you can write to the necessary areas on the NAND, which would be "busy" while android is booted. This offers a way to access the necessary partitions and write data to them while the data is not being accessed. It's also useful for backing up your NAND. Hence the name "nandroid."
3: ROM. By definition, it means "Read Only Memory." This is a chip on the board. ROM has evolved over the years. It started out as a chip that was sensitive to UV light. The earliest ROMs were "flashed" to a device by stenciling out the pathways and exposing the chip to UV radiation. Nowadays, we have fancy EEPROMs instead, which stands for Electronically Erasable Programmable Read Only Memory. This means that you can "flash" the chip by means of software, namely via Recovery mode in our case. Different ROMs have different features. They are all variations on source code made available by AOSP, or the android open source project. Some projects have their own code tracking, such as CyanogenMod. In most devices, you must be rooted to be able to install a ROM, however it is not explicitly necessary. A bit vague, I suppose. Specifically the tablet I own, the WITS a81e, you can flash a ROM to it just by putting the correct files on the TF card. This is not very common with phones, however. Flashing any rom that is not just a newer version of your current ROM will require a full format. For instance, if you have cyanogenmod and switch to a Sense or Blur ROM, you must format, but if you update from CM6 to CM6.1 you will not need to wipe. How can you trust ROM's? Well the best way to know is to either roll your own, or go with CyanogenMod, as their source is freely and easily available for scrutiny and improvement, along with a nice changelog tracker.
4. Kernels. A kernel is basically the most low level part of an operating system. It interfaces directly with the processor and provides all instruction for operation. Linux is technically not an operating system, it's a Kernel. The different distributions have the Linux kernel, and use their own different User Interfaces. Different kernels in android devices can allow you to overclock. There are many choices in kernels, and the features they offer. Some features are BFS/CFS which is the priority scheduling of processes. Some kernels allow you to charge your battery differently and conserve life. These are often called battery kernels. Also, some kernels unlock extra multitouch points in certain devices. There are different versions of the linux kernel, with many improvements with each iteration. Currently, the latest kernel available that I know of for android devices is 2.6.37. The froyo default kernel was a 2.6.32. I wish I knew a bit more about kernels, however this is about all I know. Perhaps someone could help us out and expand on this a bit?
Brilliant answer not too complicated... let's see what others say....
Sent from my HTC Wildfire using XDA App
What he said...
Pyroboy1080 well said...
That pretty much covers it.
thx for the infos..
Agreed. Thanks for using the poll!
nothing to add on that, as we used to say "merci beaucoup"
Can't ROM
Gotta be something stupid......
Can't install 2.2 or 2.3. Tried two different ODIN flashers. When I do the reset I do not get the triangel with downloading in the center. I'm rooted, Have ROM Manager, Superuser, Root Explorer, Super Manager, I'm unlocked.
I have Android SDK, Congnitive 4.1, NPS, Samsung Kies,SGH I897 USB Drivers, What else? I think I have it covered. In any case I never get the download . Even if I do a "ROM Manager Install fron SD Card, the result is a screen, blue at top and yellow at bottom with the last line saying "Installing Multi- CSC. I can let it run all night, no change in ROM. Does the Captivate sold by ATT have some kind of block or filter keeping me from updating?
Current firmware is 2.1 update 1, baseband I897UCJH7, Kernel 2.6.29 [email protected] #2, Build ECLAIR.UCJH7
Thanks
To better answer your question, I first need to know what type of device you're using...
fxstsb said:
Gotta be something stupid......
Can't install 2.2 or 2.3. Tried two different ODIN flashers. When I do the reset I do not get the triangel with downloading in the center. I'm rooted, Have ROM Manager, Superuser, Root Explorer, Super Manager, I'm unlocked.
I have Android SDK, Congnitive 4.1, NPS, Samsung Kies,SGH I897 USB Drivers, What else? I think I have it covered. In any case I never get the download . Even if I do a "ROM Manager Install fron SD Card, the result is a screen, blue at top and yellow at bottom with the last line saying "Installing Multi- CSC. I can let it run all night, no change in ROM. Does the Captivate sold by ATT have some kind of block or filter keeping me from updating?
Current firmware is 2.1 update 1, baseband I897UCJH7, Kernel 2.6.29 [email protected] #2, Build ECLAIR.UCJH7
Thanks
Click to expand...
Click to collapse
didn't know where to ask this?
hello, everyone..
i have some questions, i'm hoping some of you can anwser.
I used unrevoked to root my htc desire. after that, I used alpharev to gain s-off.
everything went fine, i got the joker, the white screen that lets me pick different options..
now Í tried all those options, nothing works.
I've been searching all night for a solution, and it seems my recovery boot and rom are missing? and what I came across is installing ANDROID SDK tools, and then run fastboot to recover an image. So I installed SDK tools, but fastboot doesn't run, it says some .dll driver is missing. in the platform-tools map is that .dll driver, should i move it?
Can someone get me a step by step tutorial on how to make my desire work again? Im kind of a noob, all I needed was to make a screenshot..
Thanks in advance, it would be appreciated so much..
Pyroboy, I'm using a Samsung Captivate. In another thread someone lead me to "All in One Toolbox". The other stuff is just stuff. That allowed me to install my ROM.
I know the linux and android kernel are different, but not much if you can already chroot into ubuntu. My question is, how do I make/compile a kernel that can boot with Ubuntu NATIVELY? Not chroot, but flash to the internel memory (maybe have to cut some bloatware out for it to fit). Or could I even just use a kernel from android?
I have wondered the same thing! I would love to turn my old Evo into a dedicated BT5 device! No need for Android OS as it just slows down BT5. I am interested in looking into that but and not sure exactly atm.
I get the impression this would be a 10x greater effort than a build of Cyanogenmod.
How so? To my understanding, TECHNICALLY we could have cyanogenmod 6, correct? Since we have froyo source...but thats not the point. With a stripped down linux distro (768mb if we could merge data and system partitions together), and a kernel built for the phone (linux kernel, not android) it should be COMPLETELY possible. My question atm is, how could I compile a kernel compatible with linux (or will the android one work)?
You mean something like this?
http://forum.xda-developers.com/showthread.php?t=892877
No, thats the chroot+vnc method. Basically that runs android in a vm, which is not what I am talking about. I mean installing linux to the internal memory, completely removing android. That way linux could use all 512mb of ram, the only downside is losing android.
ugothakd said:
No, thats the chroot+vnc method. Basically that runs android in a vm, which is not what I am talking about. I mean installing linux to the internal memory, completely removing android. That way linux could use all 512mb of ram, the only downside is losing android.
Click to expand...
Click to collapse
I think that would run a heavy risk of bricking the device since you'd have to overwrite the entire memory.
Maybe, but if you just flashed the root file system to the system (256mb), you would still have the bootloader recovery etc. partitions. Or I'm not exactly sure, maybe delete the data and system partitions and create a new 768mb partition. The only problem is I cant find anything to handle the partitions, fastboot is the closest, and fastboot doesn't work/isnt supported.
You're delving into an area that already has been delved in before. Considering the fact nobody has gotten this working ever, I would go so far as to say you're wasting your time. By all mean have at it, but keep in mind you will need a linux kernel modified in such a way that it will completely support this hardware or it would be useless. Good luck to you!
Sent from my SPH-D700 using XDA Premium App
http://blogs.sonyericsson.com/wp/2011/05/06/how-to-build-a-linux-kernel/
^^^That is the type of kernel suitable for a distro like Ubuntu, correct? Building a kernel with the samsung sources using that guide, should give me a kernel that can be used with linux, correct? I don't see why it is so hard... If you can port linux to a device such as the hd2 whats so different about running it on the epic? Linux and android are very close... the only problem I'm having is finding a way to get a .img to the device.
thomasskull666 said:
You're delving into an area that already has been delved in before. Considering the fact nobody has gotten this working ever, I would go so far as to say you're wasting your time. By all mean have at it, but keep in mind you will need a linux kernel modified in such a way that it will completely support this hardware or it would be useless. Good luck to you!
Sent from my SPH-D700 using XDA Premium App
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Click to collapse
not to mention a few of the drivers are closed source and aren't likely to be compatible with any other kernel version be it one of samsung's kernels or one from linux.....that isn't to say it is impossible but definitely a hurdle
ugothakd said:
http://blogs.sonyericsson.com/wp/2011/05/06/how-to-build-a-linux-kernel/
^^^That is the type of kernel suitable for a distro like Ubuntu, correct? Building a kernel with the samsung sources using that guide, should give me a kernel that can be used with linux, correct? I don't see why it is so hard... If you can port linux to a device such as the hd2 whats so different about running it on the epic? Linux and android are very close... the only problem I'm having is finding a way to get a .img to the device.
Click to expand...
Click to collapse
the first line of that article..."Since the launch of the unlock boot loader site, we have received a lot of really great feedback."
we do not have a modified boot loader and our bootloader is a 2 stage process...i believe the first one is efuse protected...which unless exploited cannot be modified...i'm not sure what kind of checking is done to the secondary bootloader..but one mistake with either of these files you have yourself an expensive paperweight that odin will not fix (no download mode)
edit: i see that site goes on to talk about rebuilding the kernel but still important to remember that stuff about our bootloaders
So even if the kernel worked, the drivers were perfect (which wouldn't be, I know that) and I somehow got an image to the phone it wouldn't boot because of the bootloader?
http://forum.xda-developers.com/showthread.php?t=933667
It can be done but it's not an easy task. This guy has Ubuntu natively booting on the Galaxy Tab.
He's been working on it for a long time and I still don't think it's anywhere close to fully functional, it probably never will be.
Ubuntu + Mobile Phones just weren't meant to be. However.. as this shows... if you devote enough hours to something, anything is "sorta" possible.
There's a thread in the fascinate forum that's relevant to this, about building jigs.
The issue is, as you mentioned, the bootloader. Apparently, it is much like the BIOS on a PC, where you have the option to boot up from different sources. However, our bootloader has those options removed (it actually might have been disabled by hardware, but I can't remember), and only includes normal bootup, recovery kernel, and the kernel/partition that handles download mode.
Obviously you know all this. The developer there is working on a solution, and it could end up being either a software or hardware hack. I suggest you search for the thread (I would if I wasn't on my app).
However, this is relevant because his goal is different than yours, but will most likely be your solution. Rather than modifying the bootloader to handle a larger partition or a linux kernel, it would be easier to get the bootloader to do something it was intended to do back at the factory: boot from USB. There are unused pin configurations that were meant for this, and if enabled could allow a lot of possibilities. Booting ubuntu would be just the tip of the iceberg.
The developer actually has gotten as far as getting a boot log from the very first, barebone bootloader (whatever the acronym is), and shows it searching for usb host or whatever. I'm gonna see if I can dig up the link.
EDIT: er, maybe not fascinate forum, I'm having trouble finding it
Sent from my SPH-D700 using XDA Premium App
Try searching for the SGS Ubuntu attempts. I know that someonne in #ubuntu-arm has gotten it to a usable state on his SGS. However, be prepared to lose functionality.
Question is why. There won't be an accelerated X server, and if you are looking to target a embedded linux surely there are better systems out there. You'll also have to deal with the keymappings afaik because that's apparently dealt through system_server via keymaps, and not the kernel.
-- Starfox
Starfox said:
Question is why.
-- Starfox
Click to expand...
Click to collapse
Hacker Mantra: Cause you can
Why climb Mt. Everest? Cause you can.
Why put linux on every device out there? Cause you can.
tyl3rdurden said:
Hacker Mantra: Cause you can
Why climb Mt. Everest? Cause you can.
Why put linux on every device out there? Cause you can.
Click to expand...
Click to collapse
True that, it is pretty damn adaptable that's for sure.
Sent from my SPH-D700 using XDA Premium App
haha found it!
relevant http://forum.xda-developers.com/showthread.php?t=1065318
I own a tegra 2 device that can boot BT natively, I know it's nowhere close to our chipset but perhaps it could lead somebody with the right skillset down this road for the Epic; http://forum.xda-developers.com/showthread.php?t=1075054
Hello, I'm new to all this Android stuff (I don't even have a phone yet, but its on it way)
I have been reading up on custom ROM creation but there are some things I don't quite understand.
Let's say I have a phone in Android 2.3. I want to create an Android 4.0 ROM to put on the phone.
Now... to compile Android 4.0 I need the drivers for my phone (which I doubt I will ever have access too since its only a cheap Android with a MediaTek CPU)
So I have a 2.3 ROM that contains all the compiled drivers and the Android 4.0 source code.
Is it possible to compile 4.0 and replace the zImage (if I'm correct) with the 2.3 zImage. From what I have read, that's where all the drivers are stored.
I guess its not that simple since I also think the zImage contains the OS. If so, is it then possible to extract the zImage and replace the invalid driver files in 4.0 with the correct drivers from 2.3?
Also, I think my phone will arrive with an annoying UI, is it possible to just get any 2.3 ROM (that doesn't have an annoying UI and shares the same CPU as my phone) and replace the zImage in that with my phones 2.3 zImage?
Sorry, if my questions are stupid but this is all new to me. I've tryed to read up on this but nothing is straight to the point.
Thanks
Anyone there?
try out some roms first. see what you like and dont like. it'll probably give you a better idea for how you would make your own rom.
I don't think you could just port an entire zimage to ICs and say it will work (it might not even compile i think). It won't work. You could probably take some drivers' code (screen, speaker, etc), modify them a bit so it compiles, and test to so if it works. You more than likely have to modify the ICS code also so it works. And the zimage is just the kernel no? And the kernel really only has to do with low level system processes, drivers, etc. I think UI's and such are more fitted in frameworks and such.
Personally if it was so easy to port ICS by simply replacing the zimage or file with another, ICS would have been ported to many devices, fully working, by now.
Kailkti said:
I don't think you could just port an entire zimage to ICs and say it will work (it might not even compile i think). It won't work. You could probably take some drivers' code (screen, speaker, etc), modify them a bit so it compiles, and test to so if it works. You more than likely have to modify the ICS code also so it works. And the zimage is just the kernel no? And the kernel really only has to do with low level system processes, drivers, etc. I think UI's and such are more fitted in frameworks and such.
Personally if it was so easy to port ICS by simply replacing the zimage or file with another, ICS would have been ported to many devices, fully working, by now.
Click to expand...
Click to collapse
Yeh, but my problem is I don't have the drivers for the phone. I just have the stock ROM that come with it.
Is not that simple. I am 99% sure that you can't do that.
The phone I'm getting has a horrible theme on it. Its running Android 2.3
I have the ROM for a very similar phone (also using Android 2.3), uses the exact same CPU so it should be compiled using the correct platform.
Is it possible to use that phones ROM but replace it with my phones Kernel and .prop (so it has all my phones drivers and settings etc...)?
the hard work required in making a custom rom
I think you can take from the stock rom and compared with existing custom rom
but some sources are not shared freely as an example Tegra
CMIIW
I will mess about with the ROM when I get my phone. Hopefully I wont brick it...
I too am fairly new to android. I spent a couple weeks reading and watching TONS of youtube videos on how to ROOT and Unlock my bootloader. My best advice from one n00b to another would be to do the same. In particular...research how to do it on YOUR phone. Also, Roms are device specific. I recommend you finding the forum here on XDA for your phone and read up on whatever ROMS are available here. This might not be the ONLY place to find ROMS, but this place simply rocks! Once you get your device rooted and if necessary, your bootloader unlocked...you can easily try out any ROM without much fear. Just make a good backup...make sure you also have a factory recovery image too...just in case. For backups...if you install and use Clockwork Mod (CWM) you can use the nandroid backup it offers. I bought Titanium backup from the market and used it to do a full backup before I started...it backs up to dropbox even, which was a nice feature for me. Extra safety so incase I hosed my external SD card which had my backups...I could easily retrieve a backup ANY place that had internet access. Lastly...get ready to have some FUN! Flashing ROMs is VERY addictive!! :-D
Ok, Thanks. I will see what I can do then.