On 28.03.2024 16:35, Roger Pau Monne wrote: > There's no reason to assume VGA text mode 3 to be unconditionally available. > With the addition of booting Xen itself in PVH mode there's a boot path that > explicitly short-circuits all the real-mode logic, including the VGA > detection. > > Leave the default user selected mode as text mode 3 in boot_vid_mode, but do > not populate boot_vid_info with any default settings. It will either be > populated by the real-mode video detection code, or left zeroed in case > real-mode code is skipped. > > Note that only PVH skips the real-mode portion of the boot trampoline, > otherwise the only way to skip it is to set `no-real-mode` on the command > line, > and the description for the option already notes that VGA would be disabled as > a result of skipping real-mode bootstrap. > > This fixes Xen incorrectly reporting: > > (XEN) Video information: > (XEN) VGA is text mode 80x25, font 8x16 > > When booted as a PVH guest.
And what effect does this have on a bare-metal boot with no-real-mode in use? The default on x86 hardware still is that in the absence of other information, a VGA of some kind can be assumed to be there. Yes, there are headless systems, but better assume VGA is there when there's not than the other way around. What I would have expected is for the PVH boot path to clear boot_vid_info. Jan
