PC System Flash emulation was added for QEMU in pc-1.1. It is currently not supported by KVM.

Flash Hardware

Uses CFI flash support in hw/pflash_cfi01.c.

Command line interface

Usage of -bios and -pflash parameters as of pc-1.1:

KVM enabled	-pflash used	-bios used	Result
No	Yes	-	-pflash parameter will be loaded as flash image just below 4GB. 'bios.bin' and -bios parameter will be ignored.
	No	No	'bios.bin' will be used to create a read-only pflash drive. A flash device is available, but it is read-only.
	No	Yes	-bios parameter will be used to create a read-only pflash drive. A flash device is available, but it is read-only.
Yes	Yes	-	An error message condition: PC system firmware (pflash) not available
	No	No	'bios.bin' will be loaded as rom image. No system flash is available.
	No	Yes	-bios parameter filename will be loaded as rom image. No system flash is available.

The flash image can be any drive image format supported by QEMU.

There are two ways to add the pflash drive when launching qemu-system-i386 or qemu-system-x86_64:

KVM support is being investigated, but it will require modification of KVM (kernel + qemu) to enable KVM read-only page support.