Updating boot partitions for the volume is required
Regular users should probably avoid this option unless the preceding procedure does not work—and in that case, you should disable SIP temporarily and then re-enable it when you've finished installing r EFInd.
On this page, I describe two methods of disabling SIP: using OS X's Recovery HD system and using r EFInd on CD-R or USB flash drive.
Instead of locating and running the This command will disable SIP for all OSes that honor this setting.
(In theory, multiple versions of OS X might be installed on a single computer, and all of them that support SIP should honor the SIP settings.
This page covers these two options in more detail, as well as a third: Using another OS to install r EFInd.To the best of my knowledge, no non-Apple OS honors SIP settings, although that could change.) Once you've typed this command, you can reboot the computer.