Question on boot device information

[Felipe Franciosi]

Hi all,

I have a doubt around what information grub provides to initramfs
regarding the boot device (Linux). IIUC, grub uses the system's
firmware (or its own drivers?) to load the kernel and initramfs, later
jumping into the kernel entry point.

At that point, what information does initiramfs has about where it was
loaded from?

In the simple case where both the kernel and the initramfs came from
an NVMe drive (or a disk behind a PCI SCSI controller), is it possible
for initramfs to find out that device's BDF?

I am trying to prevent certain drivers from binding to all devices at
that stage and would like to configure my initiramfs to load the
required driver but only bind to the device which contains the root
filesystem (which, in my case, will be the same as the kernel and
initiramfs).

Thoughts, pointers, and clarifications welcome. :)

F.