Can someone explain a/b and twrp simply

[motolio]

Is there a sticky about why twrp is so hard to tackle with this phone? If not, can someone explain the concept of the a/b stuff and how/why it affects the twrp process.?
Thank you!

 

[Spaceminer]

Is there a sticky about why twrp is so hard to tackle with this phone? If not, can someone explain the concept of the a/b stuff and how/why it affects the twrp process.?
Thank you!

A/B is like having dual boot on a PC. The major difference here is the /data partition is shared with both slots. It makes everything a pain in the ass if you ask me.

For instance... You can keep two different operating systems on the device at once, but if the data isn't 100% compatible between both you're going to have a horrible time. I tried keeping stock on one slot, and using the other for GSIs. Sounds like a great idea but it really isn't. You have to format data if you switch.

This is where twrp problems also come in... Not so much twrp itself but Motorola I guess. On my current device at least, the G7 Play, Motorola is using something called "forward error correction". It makes it impossible for twrp to be installed on the same slot as the stock OS. It also makes it impossible for twrp to restore the stock OS. We have to flash the entire firmware and erase userdata. Everything works perfectly if a GSI is installed though. I don't know if that's a problem for the G7 Power but it is for us.

Another issue is that Magisk and twrp don't play nice with each other. I can't for the life of me get both installed at the same time. It's one or the other, but not both. That's because traditionally magisk was installed to the ramdisk of the boot.img. So when Google merged boot and recovery into one image, magisk went along with it. This wouldn't normally be an issue, but for reasons unknown to me (probably ota related), Topjohnwu decided to make Magisk have an off/on switch. Reboot to recovery, you get a system rooted with magisk. Reboot normally, no root. This breaks twrp because obviously you need to reboot into recovery for twrp to work. If it was designed so that you're rooted when you boot normally it wouldn't be a problem. Another solution is "system root", which only Phh has at the moment. It works great on his GSIs, but it's not an every day solution for stock.

I hope this is the kind of info your were after.

 

[WoKoschekk]

Is there a sticky about why twrp is so hard to tackle with this phone? If not, can someone explain the concept of the a/b stuff and how/why it affects the twrp process.?
Thank you!

In the post before some facts have been mixed up.
The Moto G7 Power is a A/B device. It has two slots (_a and _b) for every important partition such as /system, /vendor, /boot, /oem and some others. That means the device has them double.
What's the purpose and how does it effect the partition layout?
With a A/B device you can install an OTA update in background while your system is running as usual. You do not have to boot into recovery anymore to install it. While running on slot _a the update is being installed on slot _b. When the update is successfully installed you just reboot into the "new" OS on slot _b. The new boot slot will be set automatically by system.
For us, the users, this new concept is very handy because we can still use the device and don't have to wait. That's the purpose of a A/B device. But what has been changed?
Well, as I said before, you don't need a recovery for the update process. So Google removed the dedicated recovery partition and merged it into the boot partition or rather into the ramdisk of the boot partition. But where to flash TWRP now? To install TWRP you must override the stock recovery - inside the boot partition. Fastboot can't handle it since you need to unpack the boot.img, override recovery and repack the boot.img again. But fastboot has the option to boot any kernel from a external source, such as TWRP. And what a luck: TWRP contains terminal binaries to un- and repack a boot.img to install itself!
That's the reason why you have to boot TWRP first to install TWRP through TWRP!

 

[roadkill42]

In the post before some facts have been mixed up.
The Moto G7 Power is a A/B device. It has two slots (_a and _b) for every important partition such as /system, /vendor, /boot, /oem and some others. That means the device has them double.
What's the purpose and how does it effect the partition layout?
With a A/B device you can install an OTA update in background while your system is running as usual. You do not have to boot into recovery anymore to install it. While running on slot _a the update is being installed on slot _b. When the update is successfully installed you just reboot into the "new" OS on slot _b. The new boot slot will be set automatically by system.
For us, the users, this new concept is very handy because we can still use the device and don't have to wait. That's the purpose of a A/B device. But what has been changed?
Well, as I said before, you don't need a recovery for the update process. So Google removed the dedicated recovery partition and merged it into the boot partition or rather into the ramdisk of the boot partition. But where to flash TWRP now? To install TWRP you must override the stock recovery - inside the boot partition. Fastboot can't handle it since you need to unpack the boot.img, override recovery and repack the boot.img again. But fastboot has the option to boot any kernel from a external source, such as TWRP. And what a luck: TWRP contains terminal binaries to un- and repack a boot.img to install itself!
That's the reason why you have to boot TWRP first to install TWRP through TWRP!

So there is no stock recovery in a sence now?

 

[sd_shadow]

So there is no stock recovery in a sence now?

There's no separate partition for recovery, stock nor TWRP.

Sent from my Moto E (4) using Tapatalk

 

[WoKoschekk]

https://www.xda-developers.com/how-...ess-updates-affect-custom-development-on-xda/

 

[flash713]

Just came across this. https://www.androidpolice.com/2020/...tes-on-devices-launching-with-android-11/?amp

Sent from my [device_name] using XDA-Developers Legacy app

 

[motolio]

https://www.xda-developers.com/how-...ess-updates-affect-custom-development-on-xda/

Thank you! Exactly what I was looking for

 

[motolio]

In the post before some facts have been mixed up.
The Moto G7 Power is a A/B device. It has two slots (_a and _b) for every important partition such as /system, /vendor, /boot, /oem and some others. That means the device has them double.
What's the purpose and how does it effect the partition layout?
With a A/B device you can install an OTA update in background while your system is running as usual. You do not have to boot into recovery anymore to install it. While running on slot _a the update is being installed on slot _b. When the update is successfully installed you just reboot into the "new" OS on slot _b. The new boot slot will be set automatically by system.
For us, the users, this new concept is very handy because we can still use the device and don't have to wait. That's the purpose of a A/B device. But what has been changed?
Well, as I said before, you don't need a recovery for the update process. So Google removed the dedicated recovery partition and merged it into the boot partition or rather into the ramdisk of the boot partition. But where to flash TWRP now? To install TWRP you must override the stock recovery - inside the boot partition. Fastboot can't handle it since you need to unpack the boot.img, override recovery and repack the boot.img again. But fastboot has the option to boot any kernel from a external source, such as TWRP. And what a luck: TWRP contains terminal binaries to un- and repack a boot.img to install itself!
That's the reason why you have to boot TWRP first to install TWRP through TWRP!

Dude. You f*ckin' broke. it. down! Thank you so much. I finally get it.
I'm not a fan of just following a tutorial and calling it a day. I like to understand how a process acheives a goal (atleast when gooning on a phone for hours). So, thank you for laying out like that!!