URL: <https://savannah.gnu.org/bugs/?56217>
Summary: Grub2 Booting in blind mode due to "invalid video mode specification `text'" Project: GNU GRUB Submitted by: decui Submitted on: Thu 25 Apr 2019 08:17:16 PM UTC Category: Booting Severity: Major Priority: 5 - Normal Item Group: Software Error Status: None Privacy: Public Assigned to: None Originator Name: Originator Email: Open/Closed: Open Discussion Lock: Any Release: Release: Git master Reproducibility: Every Time Planned Release: None _______________________________________________________ Details: 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 hence I'm reporting this bug to track the issue. :-) Once the fix is in the upstream grub, it would easier to ask the other Linux distros, e.g. RHEL 7.6, to also integrate the fix. _______________________________________________________ Reply to this item at: <https://savannah.gnu.org/bugs/?56217> _______________________________________________ Message sent via Savannah https://savannah.gnu.org/ _______________________________________________ Bug-grub mailing list Bug-grub@gnu.org https://lists.gnu.org/mailman/listinfo/bug-grub