Resurrecting fbdev

Posted Jan 20, 2022 6:17 UTC (Thu) by error27 (subscriber, #8346)
Parent article: Resurrecting fbdev

The fbdev subsystem has needed a maintainer for a years. It's a super frustrating subsystem because when you report bugs the attitude is "Yeah. Fbdev is a known root exploit so who cares if it crashes a bit?"

For example, here are some bugs I reported back in 2014.
https://marc.info/?l=kernel-janitors&m=13906030980688...

Here is the fix for that from last December but it still has not been applied. I asked George Kennedy to wait for a bit and resend it through Andrew Morton.
https://lkml.org/lkml/2021/12/7/1040

On the other hand, I really don't want the accelerated scrolling patch to be revived. The main problem with fbdev is all the crashing and the memory corruption bugs. Memory corruption bugs confuse syzbot so instead of showing up as one bug, it shows up as dozens of crazy bugs in random parts of the kernel. It's horrible and we spent a long time fixing it. Let's not go backwards.

Resurrecting fbdev

Posted Jan 20, 2022 9:05 UTC (Thu) by blackwood (guest, #44174) [Link] (3 responses)

From drm side we do care a bit about fbdev, but it's extremely limited to just the core code, fbcon, and the handful of firmware drivers that run before drm drivers take over.

So yeah any driver patches for something like cirrusfb tend to get ingored. Run the drm/cirrus driver instead, if that blows up there will be people who take a look.

The thing _is_ a root exploit pretty much end-to-end :-/

Resurrecting fbdev

Posted Jan 20, 2022 10:56 UTC (Thu) by ballombe (subscriber, #9523) [Link] (1 responses)

> The thing _is_ a root exploit pretty much end-to-end :-/

If this is the case, there is nothing Deller can do to make it worse.
Since KMS made all but impossible to use the VGA console, all systems are running fbdev now.
I for one, am happy there is a new maintainer that see fbdev as something else as a liability.

Resurrecting fbdev

Posted Jan 28, 2022 3:23 UTC (Fri) by HelloWorld (guest, #56129) [Link]

> If this is the case, there is nothing Deller can do to make it worse.

Of course there is. He can make people think that using fbdev is a reasonable idea because, after all, it is being maintained now! Or he can delay the removal of that code.

This whole situation is very unfortunate. Just let it die already.

Resurrecting fbdev

Posted Jan 20, 2022 10:56 UTC (Thu) by error27 (subscriber, #8346) [Link]

Huh... I know that patching fbdev is a waste of time, but sometimes code annoys me so much that I just fix it anyway. I just looked at my outbox and I discovered that *none* of my fbdev patches from 2021 were applied.

I sent four patches to fbdev in 2021. In one case, the original author fixed his bug before me so that's fine. In another case, my patch was Acked but not applied. And for the remaining two patches I was just ignored. There is no other subsystem right now that's as bad as that.

It's such a discouraging thing because newbies are like:

Step 1: Find an easy bug
Step 2: Fbdev hasn't applied bugfixes for years so it has the most obvious bugs
Step 3: Send a patch
Step 4: Wait for feedback before going further
Step 5: Die of old age