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
