| 1 |
On 20/07/02 08:05AM, Benda Xu wrote: |
| 2 |
> >> Could you please remind me why we need a bootstrap-init? Can we just |
| 3 |
> >> exec the Android init when the lxc-guest starts? |
| 4 |
> > |
| 5 |
> > Yeah sure. Apparently, Android needs to parse its device tree for early |
| 6 |
> > mounting partitions, before exec'ing `init`. Plus even before dealing |
| 7 |
> > with the dt, we need to mount `/system` and switch root to it. |
| 8 |
> > I could create the environment for "using /system as root" w/o the help |
| 9 |
> > of `bootstrap-init` but I couldn't deal with the device tree easily. |
| 10 |
> > |
| 11 |
> > `bootstrap-init` creates the entire environment for android to boot from |
| 12 |
> > scratch and then finally exec's `init`. So I proposed to use it instead |
| 13 |
> > of manually setting up the LXC container for system-as-root devices. |
| 14 |
> > That way the setup is clean as we only need a /dev directory and a static |
| 15 |
> > `bootstrap-init` binary inside of the LXC rootfs. |
| 16 |
> |
| 17 |
> In principle you can choose your way of achieving things. But |
| 18 |
> considering you got stuck in making a functional 'bootstrap-init', I |
| 19 |
> have 2 questions. |
| 20 |
|
| 21 |
I would like to clarify first that bootstrap-init works fine, but due to |
| 22 |
the nature of build-system it requires, I was having difficulties in |
| 23 |
compiling it natively in arm64 Gentoo. |
| 24 |
|
| 25 |
> 1. If you need to prepare a proper environment for Android to boot |
| 26 |
> inside the LXC guest, please check out LXC container hooks in |
| 27 |
> lxc.container.conf(5) manpage. Another init seems an overkill for |
| 28 |
> me. |
| 29 |
|
| 30 |
I was going with this approach initially, but the container configs just |
| 31 |
don't seem apt for a process like this. I mean to mount the early |
| 32 |
partitions only, I have no clue how I would approach parsing the device |
| 33 |
tree using the LXC conf. |
| 34 |
|
| 35 |
Although I had made some slight edits to the original container hook |
| 36 |
scripts, for keeping the rootfs clean after reboots and more. You could |
| 37 |
check the modified scripts in [1]. |
| 38 |
|
| 39 |
> 2. Why bootstrap-init needs to be written in C++? Would a shell script |
| 40 |
> enough? |
| 41 |
|
| 42 |
I followed Magisk's approach of booting SAR Android. I thought of |
| 43 |
rewriting the entire init but realised that that would be rather |
| 44 |
inefficient. Therefore, I stripped all the "Magisk-y" code and put |
| 45 |
forward the bare minimum required for functioning. |
| 46 |
In theory, we could rewrite it all in shell, but then again, I would not |
| 47 |
recommend it as it could be somewhat lengthy. |
| 48 |
Moreover, this setup is scalable and it could be extended later for any |
| 49 |
new boot-scheme Android pulls up. |
| 50 |
|
| 51 |
If required by any situation, I can willingly rewrite it in shell as |
| 52 |
well. |
| 53 |
|
| 54 |
Regards, |
| 55 |
Gunwant |
| 56 |
|
| 57 |
[1] https://wantguns.gitlab.io/blog/sharkbait/starting_android_in_gentoo/#install-lxc |
Archives