Can anyone comment please, what bootloader is used on Jolla with Sailfish?

Is it possible to boot Sailfish there in verbose mode (i.e. not with the splash screen but with detailed output from the kernel, systemd and etc.)?

For example in GRUB I usually set loglevel=4 as a parameter for bootloader to get a reasonably verbose output. Nexus 7 for example uses its own closed bootloader, but you can pass kernel parameters to it (such as loglevel and others) for booting Plasma Active or Nemo.