Bootloader stuff - Android Q&A, Help & Troubleshooting

Bootloader stuff - Android Q&A, Help & Troubleshooting

Below I'm mentioning a few points that I have tried to understand in the past 2 days.....Please note these are just assumptions of my understanding...I might be wrong....Plz cement my understanding by just saying either true or false....You may correct the wrong assumptions...no force
1. Users with unlocked bootloaders and the ability to boot into the bootloader (HTC) can do without a custom recovery...as they can do all that we do through CWM using the fastboot commands through cmd. (This point is clarified a bit from ur above post. Bootloader/fastboot mode can only replace a few features of CWM not all....CWM gives more advanced features. )
2. Samsung users have unlocked bootloaders but cannot boot into it so cannot use fastboot commands. They need to flash CWM through ODIN by entering download mode.
3. Download mode exclusive to samsung.
4. fastboot commands can be used with locked bootloaders.
5. The boot.img is an image of the boot partition and same goes for recovery.img.
6. boot.img contains the kernel and the ramdisk..so the bootloader location first loads this partition into main memory and the kernel then loads the OS and other stuff.
7. HTC devices have access to bootloader (HBOOT) ie they can boot into the bootloader. From there they can use fastboot commands to direct the bootloader to boot into recovery mode....what this does is directs the bootloader to load the recovery partition into memory instead of the boot partition.
8. Samsung users cannot directly address the bootloader as they cannot boot into the bootloader and hence cannot use fastboot commands. The key combinations (Volume up + ok + Power) that sammy users use to get into recovery are directions to the bootloader to load the recovery partition instead of the boot partition.
9. On rooted phones, we can use apps to do the same thing from within the phone ie we are using apps with root access to instruct the bootloader to take us into recovery instead of using key combinations at boot.
10. Even htc users can do so apart from the ability to directly instruct the bootloader by booting into it.
Your help will be greatly appreciated
Note : Samsung here refers to mostly S2 as I know that nexus users can boot into the bootloader.

Related

Flash the boot.img FOR RUNNING my shipped phone

My problem:
http://forum.xda-developers.com/showthread.php?p=22444589
1) I cannot boot my phone, the best i can is going to the bootloader
2)USB debugging can't function since i can't boot my phone
My phone:
HTC EVO 3D GSM
Hboot 1.49.0012
LOCKED
S-ON
Thread I have read:
http://forum.xda-developers.com/showthread.php?p=22444589
http://forum.xda-developers.com/showthread.php?t=1372097
http://forum.xda-developers.com/showthread.php?t=1467293
In conclusion, I understand the following:
boot my phone to fastboot
(turn off first.make sure completely off, then press volume down and power button)
connect my phone to pc, open cmd.exe
Sth I dk how to use:
(fastboot flash boot [location of boot.img]\boot.img
5. EXTRACT the .zip file of the ROM that you are using that freezes.
6. Open the folder and copy the boot.img from that ROM
7. Paste that .img into the folder that has your adb and fastboot files for the Android SDK!
8. in terminal navigate to that folder, and do the following commands)
However, I would like to do a fastboot flash boot to solve the problem of stuck in HTC startup screen.
Difficulties: 1) .img file 2) command 3) would it "brick"? 4) KEEP SHIPPED
Targets: 1) Do not erase (mmssms.db) 2)mmssms.db backup and recovery 3) Functions my phone

Nokiawithandroid said:
My problem:
http://forum.xda-developers.com/showthread.php?p=22444589
Thread I have read:
http://forum.xda-developers.com/showthread.php?p=22444589
http://forum.xda-developers.com/showthread.php?t=1372097
http://forum.xda-developers.com/showthread.php?t=1467293
In conclusion, I understand the following:
boot my phone to fastboot
(turn off first.make sure completely off, then press volume down and power button)
connect my phone to pc, open cmd.exe
Sth I dk how to use:
(fastboot flash boot [location of boot.img]\boot.img
5. EXTRACT the .zip file of the ROM that you are using that freezes.
6. Open the folder and copy the boot.img from that ROM
7. Paste that .img into the folder that has your adb and fastboot files for the Android SDK!
8. in terminal navigate to that folder, and do the following commands)
However, I would like to do a fastboot flash boot to solve the problem of stuck in HTC startup screen.
Difficulties: 1) .img file 2) command 3) would it "brick"? 4) KEEP SHIPPED
Targets: 1) Do not erase (mmssms.db) 2)mmssms.db backup and recovery 3) Functions my phone
Click to expand...
Click to collapse
Are you CDMA sounds like your on hboot 1.5? I dunno are you gsm or CDMA?
I know CDMA users make sure you have a copy of your recovery in your adb folder...
Make sure debug is turned on
Then when your in hboot
and plugged into computer using adb...
Type
fastboot boot recovery.img
This way you can flash whatever you want rom wise without taking the boot.img out of it... Also wipe before you go flashing...... This won't brick you... Only way to brick which is hard to do is you would have to flash the wrong radios or be in the middle of a flash or radio flash and pull the battery or your battery dies.... A brick is a useless phone that won't turn back on....
No such thing as a soft brick either lol.. Those are called bootloops or aka stuck on splash screen.... As long as your phone boots to Hboot your safe...

reaper24 said:
Are you CDMA sounds like your on hboot 1.5? I dunno are you gsm or CDMA?
I know CDMA users make sure you have a copy of your recovery in your adb folder...
Make sure debug is turned on
Then when your in hboot
and plugged into computer using adb...
Type
fastboot boot recovery.img
This way you can flash whatever you want rom wise without taking the boot.img out of it... Also wipe before you go flashing...... This won't brick you... Only way to brick which is hard to do is you would have to flash the wrong radios or be in the middle of a flash or radio flash and pull the battery or your battery dies.... A brick is a useless phone that won't turn back on....
No such thing as a soft brick either lol.. Those are called bootloops or aka stuck on splash screen.... As long as your phone boots to Hboot your safe...
Click to expand...
Click to collapse
Sorry, update the status apologize for the mistakes

Any expertise?

Helpppppppppppppppp pleaseeeeeeeee!!!!!!!!!!!!!!!!!!!!! (((

Nokiawithandroid said:
My problem:
http://forum.xda-developers.com/showthread.php?p=22444589
1) I cannot boot my phone, the best i can is going to the bootloader
2)USB debugging can't function since i can't boot my phone
My phone:
HTC EVO 3D GSM
Hboot 1.49.0012
LOCKED
S-ON
Thread I have read:
http://forum.xda-developers.com/showthread.php?p=22444589
http://forum.xda-developers.com/showthread.php?t=1372097
http://forum.xda-developers.com/showthread.php?t=1467293
In conclusion, I understand the following:
boot my phone to fastboot
(turn off first.make sure completely off, then press volume down and power button)
connect my phone to pc, open cmd.exe
Sth I dk how to use:
(fastboot flash boot [location of boot.img]\boot.img
5. EXTRACT the .zip file of the ROM that you are using that freezes.
6. Open the folder and copy the boot.img from that ROM
7. Paste that .img into the folder that has your adb and fastboot files for the Android SDK!
8. in terminal navigate to that folder, and do the following commands)
However, I would like to do a fastboot flash boot to solve the problem of stuck in HTC startup screen.
Difficulties: 1) .img file 2) command 3) would it "brick"? 4) KEEP SHIPPED
Targets: 1) Do not erase (mmssms.db) 2)mmssms.db backup and recovery 3) Functions my phone
Click to expand...
Click to collapse
Seems to be conflicting information provided in the OP. Not sure the best route. Here is the information that seems to conflict, perhaps I misread?
1)If you're S-ON and LOCKED, I don't think you'll have access to use fastboot or any other HTC officially supported method of flashing the kernel. Normally, if you had previously unlocked the device to load a custom kernel and re-locked, it will show RELOCKED instead of LOCKED. Unless, you went the revolutionary route and then reflashed back to stock removing their S-OFF?
2) The kernel/boot partition will not touch the /data partition where (mmssms.db) is stored.
3) The device is pretty difficult to "brick". The common users you'll find claiming they have a brick, is generally due to their ignorance in not following proper directions to restore their device. Some find it easier to claim they "bricked" their device rather than do the proper research to resolve their issues.
4) The HTC splash screen freezing is generally either a bad/incompatible kernel or a bad/incompatible kernel/ROM combination. To fix either of this situations, the device will need to be UNLOCKED and/or S-OFF to allow write access to at least the kernel partition and, if needed, the system partition.
Hope that helps clarify some more!

joeykrim said:
Seems to be conflicting information provided in the OP. Not sure the best route. Here is the information that seems to conflict, perhaps I misread?
1)If you're S-ON and LOCKED, I don't think you'll have access to use fastboot or any other HTC officially supported method of flashing the kernel. Normally, if you had previously unlocked the device to load a custom kernel and re-locked, it will show RELOCKED instead of LOCKED. Unless, you went the revolutionary route and then reflashed back to stock removing their S-OFF?
2) The kernel/boot partition will not touch the /data partition where (mmssms.db) is stored.
3) The device is pretty difficult to "brick". The common users you'll find claiming they have a brick, is generally due to their ignorance in not following proper directions to restore their device. Some find it easier to claim they "bricked" their device rather than do the proper research to resolve their issues.
4) The HTC splash screen freezing is generally either a bad/incompatible kernel or a bad/incompatible kernel/ROM combination. To fix either of this situations, the device will need to be UNLOCKED and/or S-OFF to allow write access to at least the kernel partition and, if needed, the system partition.
Hope that helps clarify some more!
Click to expand...
Click to collapse
I am having something close to that issue. i have Hboot 1.49.0008 it is Unlocked but with s-On
now i can boot farther then the htc white. mine goes to the htc + quietly brilliant screen. then hits a boot loop.
what are my options and how do i do it?
thanks

joeykrim said:
Seems to be conflicting information provided in the OP. Not sure the best route. Here is the information that seems to conflict, perhaps I misread?
1)If you're S-ON and LOCKED, I don't think you'll have access to use fastboot or any other HTC officially supported method of flashing the kernel. Normally, if you had previously unlocked the device to load a custom kernel and re-locked, it will show RELOCKED instead of LOCKED. Unless, you went the revolutionary route and then reflashed back to stock removing their S-OFF?
2) The kernel/boot partition will not touch the /data partition where (mmssms.db) is stored.
3) The device is pretty difficult to "brick". The common users you'll find claiming they have a brick, is generally due to their ignorance in not following proper directions to restore their device. Some find it easier to claim they "bricked" their device rather than do the proper research to resolve their issues.
4) The HTC splash screen freezing is generally either a bad/incompatible kernel or a bad/incompatible kernel/ROM combination. To fix either of this situations, the device will need to be UNLOCKED and/or S-OFF to allow write access to at least the kernel partition and, if needed, the system partition.
Hope that helps clarify some more!
Click to expand...
Click to collapse
ok...then what can I do to fetch the data out or save my phone?

Nokiawithandroid said:
ok...then what can I do to fetch the data out or save my phone?
Click to expand...
Click to collapse
based on what has been said in the thread, you can flash a new system.img and that should give you access to the phone even if it starts FC like hell, all you need to do from there is to connect via adb backup the SMS database and continue with wiping everything and installing a new ROM (after you unlock of course)
just in case: once you get the system.img you need, apply it by typing
Code:
fastboot flash system [x:\path to file\]system.img
That should help you out.

megabiteg said:
based on what has been said in the thread, you can flash a new system.img and that should give you access to the phone even if it starts FC like hell, all you need to do from there is to connect via adb backup the SMS database and continue with wiping everything and installing a new ROM (after you unlock of course)
just in case: once you get the system.img you need, apply it by typing
Code:
fastboot flash system [x:\path to file\]system.img
That should help you out.
Click to expand...
Click to collapse
How can i flash the system.img? My phone isn't rooted or unlocked. It's totally original. Also, no way to get the debug or adb. The only connection I've got is the "fastboot usb" at the htc original bootloader.
Hopeless, right?

Nokiawithandroid said:
How can i flash the system.img? My phone isn't rooted or unlocked. It's totally original. Also, no way to get the debug or adb. The only connection I've got is the "fastboot usb" at the htc original bootloader.
Hopeless, right?
Click to expand...
Click to collapse
You posted this same question in a separate thread: http://forum.xda-developers.com/showthread.php?t=1525176
In an effort to keep the threads organized, I answered in that thread as follows:
Background on system.img: The system partition is generally only distributed in the system.img format for stock system images. Most aftermarket ROMs perfer to distribute their system content in the form of an update .zip file.
Background on bootloader: The system.img can't be flashed until you unlock the device. This is a standard security feature on any device with a "locked" bootloader, as yours shows from the information you posted.
One option: Once the bootloader is unlocked, the command should be as simple as: fastboot flash system c:\system.img
Hope that helps. Good luck!
Click to expand...
Click to collapse
Not sure how many times this can be repeated or how many different ways the same thing can be repeated. Without unlocking the device, HTC will not allow you to selectively modify any of the partitions from the bootloader or fastboot.
With these three conditions:
1) Without unlocking the device
2) Having the device freeze on the HTC splash screen
3) Never having previously loaded a custom recovery
The only option HTC provides is to run the RUU which will return the device to 100% stock erasing all information currently on the device.
If you're able to unlock the device (condition #1), you would be able to either flash a custom recovery (condition #3), or a stock/new system.img which would allow you access to the device where you can retrieving the stored SMS and MMS.
Using the stock RUU should resolve condition #2, if it didn't, there could be a more serious hardware issue with the device.
I might have missed some aspect. I'm sure somebody will post up if I did.
Hope that helps make more sense!

How to flash recovery without

Hello,
I have a crappy Samsung S4 copy (MT6575 GT-I9500, see info.jpg) that I would like to hack.
After reading a few posts if I understand correctly, the first step is to set a correct recovery image to be able to flash a custom ROM.
I have already done it on an HTC using fastboot (I use Linux), so the step was to go to the bootloader and use
Code:
fastboot flash recovery recovery.img
However, the bootloader I get does not seems to accept this command (get "< waiting for device >", see bootloader.jpg).
Using adb, I was able to access the recovery mode (abd reboot recovery) but I get "e3" recovery (see recoevery1.jpg) but I get the same empty screen whatever option I use (see recoevery2.jpg.
Any idea how I can flash a custom recoevery and/or ROM ?
Thanks

Softbrick with no custom recovery

I messed up i tried to reflash my phone back to stock from marshmallow rom on the thread here but i lost custom recovery and only thing i can get into is download mode, how can i fix this? I have abd install on my pc got the system image boot and recovery img but don't know what 2 do. Please help

xavier55 said:
I messed up i tried to reflash my phone back to stock from marshmallow rom on the thread here but i lost custom recovery and only thing i can get into is download mode, how can i fix this? I have abd install on my pc got the system image boot and recovery img but don't know what 2 do. Please help
Click to expand...
Click to collapse
Your phone is in fastboot mode, not download mode. Small, but distinct difference.
Since you've installed a custom ROM, your bootloader should be unlocked. However, it may be a good idea to issue the oem unlock command through fastboot anyways. Use "adb reboot bootloader" and "fastboot oem unlock" to ensure that your bootloader is unlocked.
Now, since your phone is in fastboot mode, you can do one of two things: 1. Flash a custom recovery and restore your device to stock, or 2. Flash a custom recovery and continue using a custom ROM. Either way, you will need to install TWRP or another custom recovery image of your choice. The TWRP thread is located here: http://forum.xda-developers.com/tmobile-lg-v10/development/recovery-unofficial-twrp-t3239740 Since you're already in the bootloader/fastboot mode, all you would need to do is download TWRP and use "fastboot flash recovery twrp.img" and then "fastboot boot twrp.img" to install TWRP. Please note that the 'twrp.img' will vary depending on which version you download, it will probably look more like 'twrp-2.8.7.1-h901.img'. You can just rename the file or use the full file name in the fastboot commands.
Once in TWRP, you can flash whatever ROM you want. To restore your phone to stock, go to this thread and flash the .zip in TWRP http://forum.xda-developers.com/tmo.../lg-h901-stock-images-device-restore-t3241170 after doing the standard wipe procedure. :good:

soltheman said:
Your phone is in fastboot mode, not download mode. Small, but distinct difference.
Since you've installed a custom ROM, your bootloader should be unlocked. However, it may be a good idea to issue the oem unlock command through fastboot anyways. Use "adb reboot bootloader" and "fastboot oem unlock" to ensure that your bootloader is unlocked.
Now, since your phone is in fastboot mode, you can do one of two things: 1. Flash a custom recovery and restore your device to stock, or 2. Flash a custom recovery and continue using a custom ROM. Either way, you will need to install TWRP or another custom recovery image of your choice. The TWRP thread is located here: http://forum.xda-developers.com/tmobile-lg-v10/development/recovery-unofficial-twrp-t3239740 Since you're already in the bootloader/fastboot mode, all you would need to do is download TWRP and use "fastboot flash recovery twrp.img" and then "fastboot boot twrp.img" to install TWRP. Please note that the 'twrp.img' will vary depending on which version you download, it will probably look more like 'twrp-2.8.7.1-h901.img'. You can just rename the file or use the full file name in the fastboot commands.
Once in TWRP, you can flash whatever ROM you want. To restore your phone to stock, go to this thread and flash the .zip in TWRP http://forum.xda-developers.com/tmo.../lg-h901-stock-images-device-restore-t3241170 after doing the standard wipe procedure. :good:
Click to expand...
Click to collapse
I'm kinda in the same boat now except that I already received the replacement device. Need to re-lock the old V10, but adb won't recognize my device at all. Any more option when that's the case? I can get into both download mode and fastboot. Phone is recognized by LGUP in download mode, but not by adb in fastboot mode for some reason.
(I've verified connection and driver using the other V10, the other V10 is recognized just fine)

baymon said:
I'm kinda in the same boat now except that I already received the replacement device. Need to re-lock the old V10, but adb won't recognize my device at all. Any more option when that's the case? I can get into both download mode and fastboot. Phone is recognized by LGUP in download mode, but not by adb in fastboot mode for some reason.
(I've verified connection and driver using the other V10, the other V10 is recognized just fine)
Click to expand...
Click to collapse
Yep. Your phone boots and everything, correct? Just factory reset it (Settings > Backup & Restore > Factory data reset). After its been reset, unlock it, turn on Developers Options, and enable USB debugging. After usb debugging is turned on, connect the v10 to your PC and be sure to hit "Always allow" when prompted by your phone. ADB should now be able to see your device.
If you can't get it to boot up, try restoring through LG UP/Bridge. I don't use any of LG's software, so I'm not sure what those apps can do and whether or not you'll be able to restore through them.
If nothing else, your phone is recognized in fastboot mode, so you can always manually flash the stock system images as well. You want to use the "fastboot flash boot boot.img", "fastboot flash recovery recovery.img", and "fastboot flash system system.img" commands After downloading the stock system images located in this thread: http://forum.xda-developers.com/lg-v10/development/lg-h901-stock-img-files-boot-recovery-t3238638
If you haven't ever flashed system images from fastboot, please read this first, as I am not responsible if your phone turns into a paperweight! https://developers.google.com/android/nexus/images#instructions While the instructions are for nexus devices, it works pretty much the same, except you'd want to use the individual commands instead of a flash-all script.
Hope this helps!

soltheman said:
Yep. Your phone boots and everything, correct? Just factory reset it (Settings > Backup & Restore > Factory data reset). After its been reset, unlock it, turn on Developers Options, and enable USB debugging. After usb debugging is turned on, connect the v10 to your PC and be sure to hit "Always allow" when prompted by your phone. ADB should now be able to see your device.
If you can't get it to boot up, try restoring through LG UP/Bridge. I don't use any of LG's software, so I'm not sure what those apps can do and whether or not you'll be able to restore through them.
If nothing else, your phone is recognized in fastboot mode, so you can always manually flash the stock system images as well. You want to use the "fastboot flash boot boot.img", "fastboot flash recovery recovery.img", and "fastboot flash system system.img" commands After downloading the stock system images located in this thread: http://forum.xda-developers.com/lg-v10/development/lg-h901-stock-img-files-boot-recovery-t3238638
If you haven't ever flashed system images from fastboot, please read this first, as I am not responsible if your phone turns into a paperweight! https://developers.google.com/android/nexus/images#instructions While the instructions are for nexus devices, it works pretty much the same, except you'd want to use the individual commands instead of a flash-all script.
Hope this helps!
Click to expand...
Click to collapse
Thanks for the follow up! No the phone would not boot at all and kept stuck at boot loop. I ended up just doing the OEM Lock and call it a day, the old device just won't boot to anything at this point.
I tried fastboot flash recovery recovery.img but it's giving some kinda kernel panic message and I was never able to get into recovery. This reminds me of the time when my Note 3 eMMC was fried, it wouldn't give a device ID to adb.

I think I am in the same boat too. I've been OEM unlocked yet recently my phone won't keep the TWRP recovery and keeps putting me into bootloop. I can't install a ROM and only thing I can do is fastboot mode. What did you do OEM lock the device? I am hoping that solution will get rid of that message bootloader unlocked during the bootloop and then I can try and get it serviced.

Rooting and Installation concepts common to all phones.

Dear All,
I went through the book "XDA Developers' Android Hacker's Toolkit".
Liked it. But got little confused too since I lack good knowledge in Android voo doo.
Is there any document or post where Rooting and Installation concepts common to all phones are discussed in detail?
Such as...
To my knowledge, we have three major pieces of software in any Android phones.
1. bootloader (mostly locked)
2. recovery
3. Android OS
1. How to replace each software when phone is not hard bricked but Android OS not working?
2. How to replace each software when phone is alive and Android OS is working?
3. If bootloader itself is corrupted?
4. If bootloader is fine but recovery corrupted?
5. If bootloader and recovery is fine but Android OS is corrupted?
6. Do installable binary differs depending on method?
etc etc...
Sincerely,
Srinivas Nayak

1. How to replace each software when phone is not hard bricked but Android OS not working?
- By using fastboot/download mode and flashing stock firmware (system+boot+recovery+bootloader) using PC
- Here either /system, /data or /boot will be corrupted.
2. How to replace each software when phone is alive and Android OS is working?
- By using fastboot or download mode and flashing stock fastboot firmware using PC.
- By using recovery mode and flashing recovery firmware zip using TWRP.
- By using ADB and flashing recovery firmware zip using ADB sideload.
3. If bootloader itself is corrupted?
- Here the fastboot mode wont be accessible
- By using emergency download mode (EDL)and flashing stock fastboot firmware using PC
- Also known as EDL mode for Qualcomm devices and download mode for Samsung and MediaTek devices
4. If bootloader is fine but recovery corrupted?
- Here the recovery mode wont be accessible.
- By using fastboot/download mode and flashing stock fastboot firmware using PC.
5. If bootloader and recovery is fine but Android OS is corrupted?
- Here the /system or /boot will be corrupted.
- By using fastboot/download mode and flashing stock fastboot firmware using PC.
- By using recovery mode and flashing recovery firmware zip using TWRP.
6. Do installable binary differs depending on method?
Didnt get your question. Which installable binary are you referring to?

Dear SharkcpN,
My hearty thanks for your valuable time and kind help.
It is very clear and concise. Simply loved it.
If you get little time, kindly help me in some silly doubts I always get confused about.
SharkcpN said:
1. How to replace each software when phone is not hard bricked but Android OS not working?
- By using fastboot/download mode and flashing stock firmware (system+boot+recovery+bootloader) using PC
- Here either /system, /data or /boot will be corrupted.
Click to expand...
Click to collapse
Here we say, stock firmware = (system+boot+recovery+bootloader)
What is the difference between boot and bootloader?
Is boot = vmlinuz? and bootloader = grub?
Can I draw an analogy of a Linux system with Android where, bootloader = grub, boot = vmlinuz, system = init, and recovery = another small rescue linux? Am I mistaken?
SharkcpN said:
6. Do installable binary differs depending on method?
Didnt get your question. Which installable binary are you referring to?
Click to expand...
Click to collapse
I was referring to this;
SharkcpN said:
2. How to replace each software when phone is alive and Android OS is working?
- By using fastboot or download mode and flashing stock fastboot firmware using PC.
- By using recovery mode and flashing recovery firmware zip using TWRP.
- By using ADB and flashing recovery firmware zip using ADB sideload.
Click to expand...
Click to collapse
in one method we say, "stock fastboot firmware",
in another method we say "recovery firmware zip".
In these two, what are these binaries?
Are they different things for different partition?
I mean, in one method what we flash, goes to /boot, in another method what we flash, goes to /system, in another method what we flash, goes to place of bootloader, in another method what we flash, goes to /recovery, or all the time, we flash only one thing that consistes of contents of all the partitions(bootloader, /boot, /system, /recovery)?
Also sometimes I read *.img file used in fastboot command, and sometimes *.zip used from recovery mode. Are the binaries same but only differently packaged?
SharkcpN said:
3. If bootloader itself is corrupted?
- Here the fastboot mode wont be accessible
- By using emergency download mode (EDL)and flashing stock fastboot firmware using PC
- Also known as EDL mode for Qualcomm devices and download mode for Samsung and MediaTek devices
Click to expand...
Click to collapse
How can we reach download mode in Samsung/MediaTek phones and EDL mode in Qualcomm phone?
I know only VolumnDown+Power to enter into fastboot mode...
Rest all of your lines are very clear since you have used all our words very consistently throughout your answer.
From all my reading of Android world, I come across a lot of inconsistency of words which resulted in a lot my confusion. This may partly have aggravated due to my lack of deep knowledge.
Kindly help.
Sincerely,
Srinivas Nayak

What is the difference between boot and bootloader?
Is boot = vmlinuz? and bootloader = grub?
Yes the /boot partition contains the Linux Kernel and the bootloader /sbl1 contains the code which is executed when the phone is started. Moto, OnePlus devices have a discrete bootloader in which you can select the partition in which you want to boot i.e. /system = Boot normally /recovery = boot into recovery mode or fastboot mode.
Can I draw an analogy of a Linux system with Android where, bootloader = grub, boot = vmlinuz, system = init, and recovery = another small rescue linux? Am I mistaken?
Correct
in one method we say, "stock fastboot firmware",
in another method we say "recovery firmware zip".
In these two, what are these binaries?
Are they different things for different partition?
They are basically the same files packaged differently. The firmware zip refers to the system (OS), boot(kernel), bootloader(grub) and other partitions which came preinstalled on your device.
Fastboot firmware consists of *.img files which are to be directly flashed using the command "fastboot flash <partition_name> <file_name.img" Recovery firmware consists of META-INF folder, system files in the form of system.dat , boot.img and other files. The META-INF folder contains a updater-script which has instructions which tell the recovery to flash file A to partition A, file B to partition B and so on. If the phone is unusable or any partition is corrupted, its better to flash all the partitions of the device in order to ensure the phone is bootable.
How can we reach download mode in Samsung/MediaTek phones and EDL mode in Qualcomm phone?
I know only VolumnDown+Power to enter into fastboot mode
For Samsung devices = Volume Down + Home + Power
MediaTek = shorting contact points on the SoC, Vol Down + Power, each brand implements it differently
Qualcomm = adb reboot edl, fastboot oem edl, Vol Up + Vol Down, shorting contact points on the SoC, Deep Flash Cable if EDL mode is blocked by the brand, again each brand implements it differently

Many thanks SharkcpN.
SharkcpN said:
Can I draw an analogy of a Linux system with Android where, bootloader = grub, boot = vmlinuz, system = init, and recovery = another small rescue linux? Am I mistaken?
Correct
Click to expand...
Click to collapse
Now my doubts got clear.
But it won't be good to disturb you further.
Is there any book, or tutorial, or any document(in any form: whether blog, website etc.) that will give me details in such line? Exactly like you stated things clearly...
I want to learn more about this...
If possible kindly share some good links.
Sincerely,
Srinivas Nayak
Yesterday's research revealed a good document: 2net.co.uk/slides/android-boot-slides-2.0.pdf
Would like to see more.

HELP ME !!! Stuck in TWRP recovery wont boot system

Hello
I 'm using Lenovo Tab 2 a7-10f
I tried to flash TWRP recovery throught fastboot.
But i didnt succeed before, so this time, i tried to enter command to open TWRP without need to install it.
___________
I entered fastboot mode via command
adb reboot bootloader
and yes, i did unlocked bootloader
___
then i used this command to put recovery in my tablet just to open that recovery
fastboot -c "lge.kcal=0|0|0|x" boot c:\twrp.img
______
i found this solution on this site
https://android.stackexchange.com/questions/86936/how-to-flash-root-zip-in-fastboot/102597
_______
And now, it is in bootloop, until i click both volume up and down , then it enters TWRP
_______
Tried to go in TWRP , Reboot > Power Off
And it shows logo and dont proccedd more, just stuck there and spining
Until i press both volume up and down, so it opens me TWRP recovery
________
Also tried to go into Reboot > System
But still same issue, not booting up at all
___
If i click Reboot > Recovery
Then it boots me back in TWRP
______
I tried already SPFlash tool before, but it doesnt detect my tablet, even if i have all drivers, and google drivers, and USB debbuging, i'm using this tablet for android app development, so it have all drivers.
_______
I managed to get my data from tablet.
I dont know what to do next.
Should i make some command from computer to boot system, using ADB, i know to use ADB, just i stucked in this weird bootloop.
_____
I'm thinking that i should flash stock ROM from TWRP while it is still alive.
Should i do that, i dont want to lose my data, i have many programs.
I dont care if i lose TWRP recovery, i dont need it after this experience right now???
What should i do

If you flash stock can you resume control and appreciate with repatching of recovery
([emoji813]9/[emoji725]/9[emoji813])

PoochyX said:
If you flash stock can you resume control and appreciate with repatching of recovery
([emoji813]9/[emoji725]/9[emoji813])
Click to expand...
Click to collapse
O, oh man, i just got shocked !!! By all this.
I understood that my problem is in boot,
because this command
fastboot -c "lge.kcal=0|0|0|x" boot c:\twrp.img
tells android that when i press power button, to boot into whatewer it is pointed to.
So this command tells android to boot recovery instead of normal system.
So i just reverted it in bootloader (fastboot) mode, by pushing command
fastboot flash boot c:\boot.img
So it booted up again ) , and also important, without losing any precious data. ))
______
It is true when people say that if everything fails in android, there is always a bootloader that you cant destroy.
And also here are commands for other partitions, in this way you can flash whole system without root or anything, for anybody who face this problem which is very hard to break without ADB, because i think even if i flash stock ROM it will boot recovery because somewhere deep inside, it is written from that bootloader,
Again, never joke with bootloader, if it dont support, it dont support and over, i dont want TWRP anymore.
Dont get in this trouble, mybe nobody will be able to fix it if he dont know how it happened.
______
Commands
_______
adb reboot bootloader (to go into bootloader)
fastboot flash boot boot.img (this is i used)
fastboot flash system system.img (this is ROM, like kitkat, or lolipop)
fastboot flash userdata userdata.img (this can be optional, it means full reset)
fastboot flash recovery recovery.img ( if on twrp , dont flash this thing if not cause problems)

indestructible master said:
O, oh man, i just got shocked !!! By all this.
I understood that my problem is in boot,
because this command
fastboot -c "lge.kcal=0|0|0|x" boot c:\twrp.img
tells android that when i press power button, to boot into whatewer it is pointed to.
So this command tells android to boot recovery instead of normal system.
So i just reverted it in bootloader (fastboot) mode, by pushing command
fastboot flash boot c:\boot.img
So it booted up again ) , and also important, without losing any precious data. ))
______
It is true when people say that if everything fails in android, there is always a bootloader that you cant destroy.
And also here are commands for other partitions, in this way you can flash whole system without root or anything, for anybody who face this problem which is very hard to break without ADB, because i think even if i flash stock ROM it will boot recovery because somewhere deep inside, it is written from that bootloader,
Again, never joke with bootloader, if it dont support, it dont support and over, i dont want TWRP anymore.
Dont get in this trouble, mybe nobody will be able to fix it if he dont know how it happened.
______
Commands
_______
adb reboot bootloader (to go into bootloader)
fastboot flash boot boot.img (this is i used)
fastboot flash system system.img (this is ROM, like kitkat, or lolipop)
fastboot flash userdata userdata.img (this can be optional, it means full reset)
fastboot flash recovery recovery.img ( if on twrp , dont flash this thing if not cause problems)
Click to expand...
Click to collapse
You good now...
([emoji813]9/[emoji725]/9[emoji813])

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