From f76317d9dc35dbc576820ba6c2a6a8e41f5338b5 Mon Sep 17 00:00:00 2001 From: Michael Chang Date: Thu, 19 May 2022 13:08:12 +0800 Subject: [PATCH] Fix infinite boot loop on headless system in qemu After finishing headless virtual machine installation via serial console, the reboot fails in grub with infinte boot loop and also keyboard input for serial console is unresponsive. The cause of infinte loop boils down to legacy vga driver in grub crashes when '-dispaly none' is used as qemu's display type described in the manual as: "Do not display video output. The guest will still see an emulated graphics card, but its output will not be displayed tothe QEMU user. This option differs from the -nographic option in that it only affects what is done with video output; -nographic also changes the destination of the serial and parallel port data." Given there's no sensible way found to skip the emulated device from the legacy vga module, we ended up removing it from all_video dependency so it wouldn't be loaded by default. In any case, the vbe module remain loaded and should fulfill the requirement of most hardwares even twenty years old or more. The unresponsive serial input is also fixed by ensuring that console input is loaded via appended so that they won't fail altogether with errors by other console device if specifying on the same list. Signed-off-by: Michael Chang --- grub-core/genmoddep.awk | 3 +++ util/grub.d/00_header.in | 10 +++++++++- 2 files changed, 12 insertions(+), 1 deletion(-) --- a/grub-core/genmoddep.awk +++ b/grub-core/genmoddep.awk @@ -98,6 +98,9 @@ } modlist = "" while (getline <"video.lst") { + if ($1 == "vga") { + continue; + } modlist = modlist " " $1; } printf "all_video:%s\n", modlist; --- a/util/grub.d/00_header.in +++ b/util/grub.d/00_header.in @@ -287,7 +287,15 @@ ;; x*) cat << EOF -terminal_output ${GRUB_TERMINAL_OUTPUT} + +for i in ${GRUB_TERMINAL_OUTPUT}; do + if [ x\${use_append} = xtrue ]; then + terminal_output --append \$i + elif terminal_output \$i; then + use_append=true; + fi +done + EOF ;; esac