How To Emulate An eMMC And SD Host Controller

[darius . mcadam]

Hello,

I'm developing a kernel for Arm64 and emulating it on QEMU. I'm using 
this version of QEMU:

QEMU emulator version 8.2.2 (Debian 1:8.2.2+ds-0ubuntu1.2)
Copyright (c) 2003-2023 Fabrice Bellard and the QEMU Project developers

I'm trying to emulate a SD host controller and an eMMC so I can test a 
SD host controller driver and an eMMC driver. Here's my emulation 
attempt:

    qemu-system-aarch64 \
    -machine virt,mte=off,virtualization=off,gic-version=3 \
    -cpu cortex-a76 -smp 8,sockets=2 \
    -m 4G \
    -device sdhci-pci,sd-spec-version=3 -device sd-card,spec_version=3

For the virt board, the sdhci-pci host controller is the only one I saw 
supported, so I decided to use that. I didn't see an eMMC device, so I 
chose sd-card. I'm hoping that I can create a drive that provides an 
eMMC image to the sd-card that will allow me to test my SD host and eMMC 
drivers. But I don't know how to create the eMMC image. I read the 
qemu-img documentation but I'm still unsure how to do this.

So, my question is, how do I correctly emulate an eMMC on the virt 
board?

Thank you,
Darius