Bootscreen resolution issue

[aci2n]

Hi everybody !
Can someone tell me if the screen resolution is fixed at boot or is it supposed to scale to my deskop screen preference ? When I start my rMBP 15" 2015, the loading bar start with a 1440x900 resolution, then halfway the screen flash briefly and the loading bar continue at my chosen resolution (1680x1050).
I have tried a lot of thing to fix it without any luck (reset PRAM/SMC, reinstall, clean install, changing resolution in root mode, safe boot, etc)
Any idea ? Maybe it's normal but in my 13" rMBP 2015 also set with a scaled resolution it boot without any problem.
Thanks !

 

[h9826790]

You can't fix it. Sierra change the timing of loading GPU driver. In the previous OS, the whole loading process was displayed by the EFI, not OS driver. And the GPU driver only kick in when switch to desktop, therefore, you can't see that "flash", and hard to tell if the loading screen is at a lower resolution.

Only the EFI can decide which resolution to use during loading, user has no way to alter it (unless you know how to dump, modify, and flash the firmware of your Mac).

In Sierra, the GPU driver will kick in about half way through of the loading screen (that's why you see the flash). No one knows why Apple suddenly change this sequence, may be they heading toward to the UEFI.

All I can say is that your Mac is absolutely normal. And there is no fix avail for this issue at this moment. If you don't want to see any resolution change during loading, the only thing you can do is to match the OS resolution to the EFI's resolution (which means 1440x900 in your case), but I don't think anyone will like this solution.

 

[aci2n]

Hi !
Many thanks for the reply and your detailed explanations.
Have a nice day !