Alberto - 2018-01-13

I recently installed rEFInd on my 27" iMac (the "late 2017" version) which has a 5k native resolution (5120x2880).

But when I first booted OS X using rEFInd, it boots into a lower resolution (3840 x 2160) on info.
I used mountesp, and edited refind.conf to manually set the native resolution ("resolution 5120 2880"), but it boots once again with the incorrect resolution. If i boot my Mac holding the option key the resolution goes okay!

Tried also with the "onlytext" option but with the same (bad) result.

Someone have any suggestions for how I might solve this problem?