hi, I made a patch to have qemu parse vga field in kernel command line and set the vid_mode field of real-mode kernel header. This patch is necessary because vga is one of the special command line options that should be parsed in bootloader, as in linux kernel Documentation/x86/i386/boot.txt. After bootloader write the passed vga value into the vid_mode field of linux real-mode kernel header, this vid_mode will be handled by linux/x86/boot/video.c in linux kernel to select vesa graphics mode, and only in this mode can vesafb be registered(in vesafb_probe()). So, if we decide to launch linux directly from qemu command line as "qemu -kernel ... -initrd... -append "..." ", (use qemu bootloader) and use vesafb as framebuffer driver, this patch to qemu is required, otherwise, the screen should just blank since the vesafb fails to register itself.
qemu.x86_boot_vidmode.patch
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