Public bug reported: In a Ubuntu 16.04.6 VM, which runs as a Gen2 VM on Hyper-V, I add GRUB_GFXPAYLOAD_LINUX="text" into /etc/default/grub and run update-grub; next, grub2 prints the below error:
error: invalid video mode specification `text'. Booting in blind mode This means grub2 passes a zero value for the "lfb_base" to Linux kernel, which then fails to reserve the framebuffer MMIO range in drivers/hv/vmbus_drv.c: vmbus_reserve_fb(); as a result, when we pass through a PCIe device to the VM, the PCIe device may get a PCI MMIO BAR in the FB MMIO range, causing a conflict, and the PCIe device can not work in the VM. The issue can not reproduce with Ubuntu 18.04. It turns out the grub2 in Ubuntu 18.04 has the below fix: video: skip 'text' gfxpayload if not supported, to fallback to default (https://git.launchpad.net/~ubuntu-core-dev/grub/+git/ubuntu/commit/?id=38d9e2f862a96a039ae8ca8b87b8615d154ceda4). I'm asking the patch author (Mathieu Trudel-Lapierre) to submit the patch to the upstream grub and this is the upstream bug link: https://savannah.gnu.org/bugs/?56217 . Here this launchpad bug is for Ubuntu 16.04 and 14.04. ** Affects: grub2 (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1826453 Title: Grub2 Booting in blind mode due to "invalid video mode specification `text'" To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1826453/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
