Re: [BISECTED] 5.14.0-rc4 broke drm/ttm when !CONFIG_DEBUG_FS

From: Duncan
Date: Mon Aug 02 2021 - 14:36:19 EST

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Mikael Pettersson <mikpelinux@xxxxxxxxx> wrote...
> Booting 5.14.0-rc4 on my box with Radeon graphics breaks with
> [drm:radeon_ttm_init [radeon]] *ERROR* failed initializing buffer
> object driver(-19).
> radeon 0000:01:00.0: Fatal error during GPU init

Seeing this here too. amdgpu on polaris-11, on an old amd-fx6100

> after which the screen goes black for the rest of kernel boot
> and early user-space init.

*NOT* seeing that. However, I have boot messages turned on by default
and I see them as usual, only it stays in vga-console mode instead of
switching to framebuffer after early-boot. I'm guessing MP has a
high-res boot-splash which doesn't work in vga mode, thus the
black-screen until the login shows up.

> Once the console login shows up the screen is in some legacy low-res
> mode and Xorg can't be started.
> A git bisect between v5.14-rc3 (good) and v5.14-rc4 (bad) identified
> # first bad commit: [69de4421bb4c103ef42a32bafc596e23918c106f]
> drm/ttm: Initialize debugfs from ttm_global_init()
> Reverting that from 5.14.0-rc4 gives me a working kernel again.
> Note that I have
> # CONFIG_DEBUG_FS is not set

That all matches here, including the unset CONFIG_DEBUG_FS and
confirming the revert on 5.14.0-rc4 works.

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