Ubuntu live USB won't start with CSM disabled
I copied files from the ubuntu-15.10-desktop-amd64.iso to a FAT32 formated USB drive. When I boot on the USB and select Ubuntu live the startup get stuck at a black screen with the message Ignoring BGRT: invalid status 0 (expected 1). Additionally it sometimes (sometimes no) cause my UEFI to boot very slow afterwards, I have to cut the power off to restore a normal speed boot (). This happens when I have CSM disabled on my motherboard, if I enable CSM and boot ubuntu in UEFI mode it starts fine.
Any idea on what is happening ?
Edit : I have to add that when CSM support is enabled the screen resolution is low while when it's disabled the resolution is high. So could this be because of some kind of graphical drivers or something ?
Edit : In the CSM compatibility menu I have 3 option :
Launch PXE OpROM Policy
Launch Storage OpROM Policy
Launch Video OpROM PolicyFor each I can chose UEFI only or Legacy Only. The only one I need to run in Legacy mode only in order to avoid the bug on ubuntu is Video OpROM policy any idea on what the problem might be ? (this is what make my screen resolution be high or low, low for Legacy, high for UEFI)
2 Answers
Okay after removing quiet from the kernel options I saw that the error message was fb : switching from nouveaufb to EFI VGA and I saw a thread on the internet that said adding nomodeset to kernel options was solving the problem and it does indeed whatever it is.
I see you've found a workaround. My suspicion is that the cause is that enabling the CSM is changing the way the EFI interacts with the video hardware. I've seen this on one of my own computers, which shows a lower-resolution display during EFI-mode booting when I activate the CSM than when it's inactive. Another possibility is that the kernel is able to use the CSM-provided video interfaces but has problems with the EFI interfaces provided by your firmware. Either situation is likely to be an indication of a firmware bug, so updating your firmware (what the manufacturer probably calls a "BIOS") may be in order.
Ordinarily, I recommend leaving the CSM disabled when you want to boot in EFI mode, since activating the CSM complicates the boot path, which creates possibilities for things to go wrong. The sort of problem you've encountered is one of the exceptions to this rule, though.
