Bug 234625

Summary:	iMac early 2008 garbled screen during install from USB stick
Product:	Base System	Reporter:	Jason W. Bacon <jwb>
Component:	kern	Assignee:	freebsd-bugs (Nobody) <bugs>
Status:	Closed Overcome By Events
Severity:	Affects Only Me
Priority:	---
Version:	12.0-RELEASE
Hardware:	amd64
OS:	Any

Description Jason W. Bacon freebsd_committer

2019-01-05 00:14:34 UTC

After loading text, data and syms, the screen switches modes and becomes unreadable.  After booting completes you can make out a blue background and whitish stripe across the middle of the screen which would be the first menu.

By booting into OS X I determined that the iMac has a Radeon GPU.

I was able to get around the problem as follows:

1. After booting to the first menu, type Ctrl+Alt+F4 to get to a shell.  The screen is still garbled here, so this alone does not help.

2. Blindly type "kldload radeonkms".  The screen then resets to a readable state.

I have not tried 11.2 on this machine, but would be willing to if it might help isolate the issue.

Comment 1 Jason W. Bacon freebsd_committer

2019-01-05 00:37:57 UTC

Followup:

Must use the same trick when booting from installed system.

To fix add the following to /etc/rc.conf:

kld_list="radeonkms"

Comment 2 Jason W. Bacon freebsd_committer

2019-01-07 20:27:15 UTC

11.2-RELEASE exhibits the same issue.

Comment 3 Jason W. Bacon freebsd_committer

2019-09-02 01:30:29 UTC

The workaround I provided here is adequate for this vintage hardware.