bootsvc is (typically) the first program loaded by usermode (contrast with userboot, which is loaded by the kernel). bootsvc provides several system services:

  • A filesystem service with the contents of the bootfs (/boot)
  • A loader service that loads from that bootfs

After preparing these services, it launches one program from the bootfs. The program may be selected with a kernel command line argument (this default to bin/devmgr currently). The launched program is provided with the bootfs mounted at /boot and the loader service. The kernel command line arguments are provided to it via envp. See the documentation in system/core/bootsvc/main.cpp:LaunchNextProcess() for more details.