kld_list="drm" (was: i915kms kernel module causing freezes on FreeBSD 13.0-RELEASE)

[Graham Perrin]

On 08/05/2021 07:10, Matt K wrote:

> On Sat, May 8, 2021 at 1:08 AM Graham Perrin <grahamperrin at gmail.com 
> <mailto:grahamperrin at gmail.com>> wrote:
>
>
>     Try a third approach:
>
>     kld_list="drm"
>
>
> This works. I will keep an eye on the system, logs, etc, and let you 
> know what I find. Now everything seems to be working as advertised. 
> With xf86-video-intel, even TearFree is working.
> Where is this behavior documented?


FreeBSD for Pretty Little Unicorns, 1st Edition.


> How did you know about this solution?


It came to me in a dream. Whispered by the ghost of Barbara Stanwyck, 
once the highest-paid woman in the United States and famed for movies 
such as 'Sorry, Wrong Number'. Lesser-known but no less valuable 
contributions to postmodern creative thinking include 'Sorry, Wrong 
Module'.


> I think that this means that my problem is solved, but the question 
> remains: why does i915kms cause freezes when loaded from rc.conf and 
> works normally when loaded by hand? This is not handbook-documented 
> behavior. Nor is it consistent or transparent.


Maybe not Intel-specific.

I find kld_list="drm" less troublesome than kld_list="radeonkms" with 
Thames [Radeon HD 7550M/7570M/7650M] with SDDM. A recent probe: 
<https://bsd-hardware.info/?probe=e90abb54c9#d10>.

My voyage of discovery spanned around three years. Maybe longer. A few 
flashbacks:

<https://lists.freebsd.org/pipermail/freebsd-current//2018-September/071327.html> 
(2018) I found kld_list="/boot/modules/radeonkms.ko" troublesome with 
FreeBSD 12.0-ALPHA7

<https://lists.freebsd.org/pipermail/freebsd-questions/2018-October/283113.html> 
(2018) "… toying with the possibility that … a specific load/start order 
might help."

<https://github.com/FreeBSDDesktop/kms-drm/issues/101#issuecomment-450776731> 
(2019) I found drm-legacy-kmod better than drm-current-kmod with 
13.0-CURRENT

<https://lists.freebsd.org/pipermail/freebsd-current/2020-November/077693.html> 
(2020) kld_list="/boot/modules/drm.ko" worked for me, keyword:

     peculiar

Eventually I condensed the working peculiarity to kld_list="drm".

More accurately (in context – SDDM, KDE Plasma and so on): 
<https://pastebin.com/4XjNFaKk> line 17.