DRM and Radeon

[Toomas Soome]

> On 26. Jan 2021, at 10:18, Marek Zarychta <zarychtam at plan-b.pwste.edu.pl> wrote:
> 
> W dniu 26.01.2021 o 08:58, Graham Perrin pisze:
>> On 26/01/2021 07:02, Alexey Dokuchaev wrote:
>> > Re: loading drm crashes system
>> > … There are known issues with Radeon cards, they were quite well
>> > supported a year ago, then something got broken. I've promised to
>> > bisect this and find the cause, but there were several
>> > syscall-related changes in -CURRENT though the course of the last
>> > year, so bisecting just the kernel is not enough (machine won't get
>> > to login prompt if the userland does not match), which cripples the
>> > process.
>> >
>> > I still intend to take this quest, just not sure when. :(
>> >
>> > ./danfe
>> Any cards in particular?
>> <https://old.reddit.com/r/freebsd/comments/kyoxmc/freebsd_quarterly_status_report_fourth_quarter/gjiw3y3/> – whilst I didn't mention Radeon there, for me it _was_ the Radeon story that seemed to improve a few months ago.
>> <https://bsd-hardware.info/?id=pci:1002-6841-103c-17a9> AMD Thames [Radeon HD 7550M/7570M/7650M]
> 
> 
> 
> For example old RS880 [Radeon HD 4200]. After deprecation of graphics/drm-fbsd12.0-kmod I found that it is still supported fine on 12-STABLE with legacy /boot/kernel/radeonkms.ko from the base. While trying the driver from graphics/drm-fbsd12.0-kmod I was not able to use this card with gdm, only startx or x11/slim worked. On 13-ALPHA this card still works fine with deprecated graphics/drm-legacy-kmod.
> 
> 

Does gdm start X in specific way? I mean, afaik, gdm is X11 client as any other, so the question would be, how does gdm get Xorg started, what is different compared to startx etc? Might it be about gdm user permissions to access drm devices?

my 2cents..
toomas