How to load a root FS?

[leahanderson1]

I've booted into the initramfs on my Apple TV HD, but I don't know how to load a root FS. Is there any way to load one be it USB, internal storage, or over the network?

[asdfugil]

It is not possible to use USB mass storage because USB host mode is not supported. Internal storage (apparently named "ANC") is also not supported. It is possible to use NFS or NBD (Network block device) using the USB Ethernet Gadget.

[asdfugil]

However, at this moment there are no good resources for booting over network on the USB gadget, netboot on postmarketOS has been broken on all devices (including android devices and stuff) for quite a while now.

[leahanderson1]

It is not possible to use USB mass storage because USB host mode is not supported. Internal storage (apparently named "ANC") is also not supported. It is possible to use NFS or NBD (Network block device) using the USB Ethernet Gadget.

I was able to get a mtd device if that's any help

[leahanderson1]

well 2
mtd0 and mtd1

[asdfugil]

well 2 mtd0 and mtd1

these are regions in RAM used to pass boot related data to linux userspace. mtd0 is m1n1 log and mtd1 a copy of Apple Device Tree

[leahanderson1]

Mind setting up a guide to do NBD?
I think you could set up a cheap little Raspberry Pi to load and serve a filesystem image over the USB ethernet gadget and get around the "no host USB" problem
and then I think you can do USB over IP too in case you want to plug in a keyboard and mouse
I mean technically you could hijack the Ethernet controller on the board since that internally uses USB 2.0 but I'm not sure if anyone would do that
plus the raspberry pi solution is a stupidly overpowered glorified USB adapter

[leahanderson1]

Apparently, there are USB over IP adapters, but somehow, they are more expensive than the jank Pi solution. And those don't even do nbd forwarding.
How was my stupid idea the best solution currently available on the market 😭😭😭😭😭

[leahanderson1]

figured at least the NBD part out, I'll try to do a PoC later that lets you pick the location of the file/block device being exposed and the port the server will run on. I'll also need to setup something in the initramfs to connect to the server over the Ethernet gadget.
In theory, this setup should work with any Raspberry Pi, including the $15 Pi Zero, or any other computer that can run Linux.
Possibly the cheapest thing you can buy that would work would be the OX64 from Pine64, however it does require external tools to flash the firmware onto it. (which is required on first getting it)

[Notalex27]

It's possible to use this as a rough guide for booting an nfs filesystem. Using the same configs for the kernel and ethbridge.sh I've gotten it to where it'll boot the filesystem and even to a full desktop, but it's very janky.

This could just be my setup or some of the stuff is broken on newer Linux distros, but the udev rules don't work and I need to modify ethbridge.sh to point to the correct network devices, and the script breaks networking on my local computer.

[Fivebuss]

By using a postmarketOS ramdisk with some tweaks to get Ethernet gadget working,

(I used the older example from a few months ago with a few minor changes)

standard NDB client/server work fine, from a linux host -> iphone

However, ext4 doesnt work. But ext2 img formatted files can be properly served over. and mounted

[Fivebuss]

Okay NFS was easier than NDB, you just need to compile the kernel with NFS enabled, and host a nfs share on the computer connected over USB to the iphone

Then you can mount it quite easily, busybox supports NFS mounts already