I am trying to create two VMs from alpine Linux image in QEMU. One for X86 and for ARM64.

For X86

qemu-system-x86_64 
-m 512 
-hda alpine_x86.qcow2 
-cdrom path/to/img.iso 
-boot d

For ARM64

qemu-system-aarch64 
-M virt 
-cpu cortex-a57 
-m 2048 
-hda alpine_arm.qcow2 
-cdrom path/to/img.iso 
-drive if=pflash,format=raw,file=flash.img  <--------- ?
-nographic

Comparing the two flows, specifying -cdrom in X86 flow is enough. But in the ARM64 case, I need to specify QEMU_EFI pflash.

I checked the ARM64 image using file and it says bootable.

file alpine-standard-3.20.1-aarch64.iso 
alpine-standard-3.20.1-aarch64.iso: ISO 9660 CD-ROM filesystem data (DOS/MBR boot sector) 'alpine-std 3.20.1 aarch64' (bootable)

However, if I do not specify the pflash, QEMU ARM VM does not come up. Why is that?