Arch Linux

gmv

Member

Registered: 2021-01-18

Posts: 4

HDMI stops working after grub upgrade, but works again by dowgrading

When I upgrade to grub-2:2.04-8 my second monitor is not detected anymore.

xrandr detects only my laptop monitor.

But if I downgrade back to grub-2:2.04-7 from my pacman cache, then the hdmi starts to work perfectly again.

Since I eventually will want to upgrade grub, I would like to know how to fix this issue.

This is my first post here. Thank you in advance.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,351

Re: HDMI stops working after grub upgrade, but works again by dowgrading

GRUB should be irrelevant when you are in xrandr /your actual system. Are you sure that's the case? Can you reproduce this across multiple reboots ? This sounds more like the race condition in loading graphics modules in which case you want to enable https://wiki.archlinux.org/index.php/Ke … _KMS_start

gmv

Member

Registered: 2021-01-18

Posts: 4

Re: HDMI stops working after grub upgrade, but works again by dowgrading

Thank you.

Yes I am 100% sure it is grub. If I upgrade, hdmi fails. If I downgrade, it works again,

The reason I even suspected that it was  grub interfering with the hdmi port was because others noticed it, see this link:

https://unix.stackexchange.com/question … t-detected

So it is a known issue with the new grub version. But I would like a permanent fix rather than having to keep the downgrade.

loqs

Member

Registered: 2014-03-06

Posts: 19,025

Re: HDMI stops working after grub upgrade, but works again by dowgrading

grub 2:2.04-8 https://github.com/archlinux/svntogit-p … 79090b21ec  prevented an exploit using grub to execute arbitrary code,  see the links in the commit message and the patch itself.

gmv

Member

Registered: 2021-01-18

Posts: 4

Re: HDMI stops working after grub upgrade, but works again by dowgrading

Thanks

loqs

Member

Registered: 2014-03-06

Posts: 19,025

Re: HDMI stops working after grub upgrade, but works again by dowgrading

The issue was fixed by starting KMS early?  If not please post the contents of Xorg.log and the output of the following from a boot using grub 2:2.04-8

# dmesg
$ xrandr

gmv

Member

Registered: 2021-01-18

Posts: 4

Re: HDMI stops working after grub upgrade, but works again by dowgrading

The issue was fixed by starting KMS early?  If not please post the contents of Xorg.log and the output of the following from a boot using grub 2:2.04-8

# dmesg
$ xrandr

Thank you!

:-)

Starting KMS early fixed the problem completely.  What a relief!!