[Bug 107441] Black or broken VT when loading i915.ko "late"

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=107441

--- Comment #12 from Jan-Marek Glogowski <glogow at fbihome.de> ---
(In reply to Chris Wilson from comment #11)
> (In reply to Jan-Marek Glogowski from comment #9)
> > So I applied the patch
> > 
> > commit 011f22eb545a35f972036bb6a245c95c2e7e15a0
> > Author: Hans de Goede <j.w.r.degoede at gmail.com>
> > Date:   Fri Apr 20 11:59:33 2018 +0200
> > 
> >     drm/i915: Do NOT skip the first 4k of stolen memory for pre-allocated
> > buffers v2
> > 
> > on top of my DRM backport and now the dmesg output is again
> > 
> > [    5.912030] [drm:intelfb_create [i915_bpo]] re-using BIOS fb
> > [    5.912121] [drm:intelfb_create [i915_bpo]] allocated 1366x768 fb:
> > 0x00000000
> > 
> > instead of the broken
> > 
> > [    4.244504] [drm:intelfb_create [i915_bpo]] no BIOS fb, allocating a new
> > one
> > [    4.244538] [drm:intelfb_create [i915_bpo]] allocated fb from stolen
> > memory
> > [    4.246099] [drm:intelfb_create [i915_bpo]] allocated 1366x768 fb:
> > 0x00040000
> > 
> > Is that what you expected?
> 
> Yes. But I'm worrying about your earlier result with 4.18rc7 as that
> includes the patch.

So I've retested the HW. The patch works on the Fujitsu U757 with the Ubuntu
12.04 + kernel 4.4 + my 4.15 DRM backport.

I'm not sure what's happening for 4.18 on the Acer n4640g HW.

* It's working when booting with i915.ko in the initramfs
* The monitor is blank, if booting with i915.ko just in the root fs

$ grep "re-using BIOS fb" dmesg-4.18*
dmesg-4.18_initramfs:[    2.042702] [drm:intelfb_create [i915]] re-using BIOS
fb
dmesg-4.18_rootfs:   [   18.468958] [drm:intelfb_create [i915]] re-using BIOS
fb

To be more precise, the "blank" screen is a monitor with backlight switched on.
I can switch to the VT with a plymouth running with the correct image, which I
didn't check earlier.

Now all of this might be a systemd or plymouth problem; but still in the
initramfs case I have a splash on the correct VT from the beginning.

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