Hi @test.test12p, welcome to Mender Hub.
I’m not completely clear on what you are asking. Where are you getting the Mender rootfs image, and for what platform is it built? We do support QEMU with Yocto builds.
In theory builds for specific platforms may be usable on various emulators but that’s more a question of the emulator and board. Mender should happily run in this environment.
If you can describe your needs in a more details, hopefully I can guide you further.
Drew