Arch Linux

xThiird

Member

Registered: 2022-05-17

Posts: 3

Can't open GRUB USB serial console on desktop pc, disk error

Hello,
I would like to interact with GRUB with a microcontroller by connecting the two with a usb to uart cable (personal learning project).

Overview of the system:
______      __________    _________
|LINUX | ---|USB-UART|---|ARDUINO|

I have two machines, an older laptop with Arch on a Samsung SSD, and a newer desktop pc with two M.2 nvme SSDs, one with Arch and the other with windows (dual boot system).

I managed to get this thing working on the laptop by using this guide and removing some commands I don't need and inputting the rest in the GRUB cli:

insmod nativedisk
nativedisk ahci
insmod ehci
insmod ohci
insmod uhci
insmod usbserial_ftdi # am using an ftdi usb to serial IC
terminal_output --append serial_usb0
terminal_input --append serial_usb0
terminfo -a serial_usb0 dumb

After these commands were executed the arduino was seeing the characters I would input into GRUB on the serial console, and viceversa was able to send characters to it.

I tried to use the same commands on the desktop pc with no success.
After I use

nativedisk ahci
ls

I see no disk in the pc, and thus the next insmods fail.

Im gonna be honest, I don't understand why I need to load the nativedisk module in the first place, but the source I linked says that it's for "not getting the disk disapearing when insmoding the *hci", and indeed that is the case on my laptop, but on the desktop they disappear anyway.

My understanding is that the ahci module is for Sata disks, and it doesn't work on my desktop because nvme drives use PCIe and not Sata.

I tried to look on the GRUB2 docs for a ''pcie" or "nvme" parameter that can be used with nativedisk, but the page doesnt list any parameters, so I don't know why using nativedisk ahci works on my laptop.

Can anybody help me out?
How do I get this to work on my desktop?

Thanks