From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michael Tremer <michael.tremer@ipfire.org>
To: development@lists.ipfire.org
Subject: Re: CONFIG_DRM_LEGACY
Date: Tue, 12 Jul 2022 12:22:24 +0200
Message-ID: <17F5F871-D0D1-4AA1-B830-5E500DED394F@ipfire.org>
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Hello,

> On 10 Jul 2022, at 13:12, Adolf Belka <adolf.belka(a)ipfire.org> wrote:
>=20
> Hi Peter,
>=20
> On 10/07/2022 12:00, Peter M=C3=BCller wrote:
>> Hello development folks,
>>=20
>> recently, it has been flagged to me that we ship our kernels with CONFIG_D=
RM_LEGACY enabled.
>=20
> Looking through Arch Linux I see that since Kernel 5.14 this option has bee=
n present. Some OS's have it enabled and some have it disabled. Arch Linux is=
 in the disabled camp and they had already removed many of the DRM based driv=
ers from their core repository.
>=20
> The result of that is that anyone needing to use old DRM based video cards =
such as Nvidia 340 and Mach64DRM have to now build the video driver themselve=
s  but also build their own kernel to set this parameter.
>=20
>> The documentation to this reads:
>>=20
>>> Enable legacy DRI1 drivers. Those drivers expose unsafe and dangerous
>>> APIs to user-space, which can be used to circumvent access
>>> restrictions and other security measures. For backwards compatibility
>>> those drivers are still available, but their use is highly
>>> inadvisable and might harm your system.
>>>=20
>>> You are recommended to use the safe modeset-only drivers instead, and
>>> perform 3D emulation in user-space.
>>>=20
>>> Unless you have strong reasons to go rogue, say "N".
>> Because of the kernel released on July 7 and its fixes to ASIX USB-to-Ethe=
rnet adapters, I
>> am currently working on that sector of IPFire 2.x anyway. Unless somebody =
of you can recall
>> why we really need to have CONFIG_DRM_LEGACY enabled, I would submit a pat=
ch disabling it -
>> its documentation does not inspire confidence at all. :-)
>=20
> I had a similar feeling when I read about it.
>=20
> I would suppose the question would be how many of the IPFire users use olde=
r DRM based video cards on their IPFire machines.
>=20
> Does IPFire include the drivers for these DRM based video cards? If not the=
n making the config disabled shouldn't give any problem.

Currently nobody is using any card with DRM. We have all modules blacklisted =
in favour of framebuffer.

I would prefer to change that, use DRM, and drop framebuffer.

Since we do not need to support all those DRM features and all cards and beca=
use all cards should support come VESA-compatibility mode, this should be saf=
e to be disabled.

I suppose Arne is the best person to comment on this.

-Michael

>=20
> That's my input from having a quick search on this topic.
>=20
> Regards,
>=20
> Adolf.
>=20
>> Thanks, and best regards,
>> Peter M=C3=BCller


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