li peter wrote:
maybe qemu-kvm use non-coreboot uses,
Correct. qemu-kvm unfortunately uses a special-case build of SeaBIOS without coreboot.
How do I do to reach my goal?
I am not sure. If SeaBIOS also has bootsplash support then you should see options in the SeaBIOS build configuration. If there are no options to enter e.g. a splash filename then probably there is no support.
SeaBIOS also runs only for a rather short time, so splash support is not very meaningful. I think it would barely be noticeable when the VM starts.
//Peter