initramfs: set resolution / rotation on bootup

Question

I have a laptop with a peculiar screen setup. The machine has an i915-based graphics adapter, and the screen is configured to be sideways by default. Everything looks good in rEFInd, but when booting up, the console output is completely garbled and sideways.

I can set the resolution by passing video=1200x1920,rotate=270 as init options, and have proper output once init is reached. But during the kernel/initramfs loading phase of the boot process, the screen is still garbled and sideways.

Is there a way to specify the resolution/rotation of the screen for the kernel/initramfs loading phase of bootup? Can I pass options at that point, or do I need to compile my own kernel?

Answer 1

Meanwhile, I was able to find a (partial) solution on my own.

At kernel start, the resolution given by the bootloader (in this case, rEFInd) is kept, or at least some parameters of it. The kernel probably uses some other method to fill the video buffer, though, leading to the garbled output.

Thus we have to change the resolution for rEFInd, e.g. in /boot/efi/EFI/refind/refind.conf:

resolution 1200 1920

Note that the width is smaller than the height. This leads to both rEFInd and the kernel output to be sideways until the init process kicks in, but that's still better than completely unreadable input.