Duncan posted on Mon, 16 Aug 2021 07:58:37 +0000 as excerpted:

Mikael Pettersson posted on Tue, 03 Aug 2021 08:54:18 +0200 as excerpted:

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On Mon, Aug 2, 2021 at 8:29 PM Duncan j.duncan@cox.net wrote:

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Mikael Pettersson mikpelinux@gmail.com wrote...

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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 system.

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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.

Yes, I have the Fedora boot splash enabled.

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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.

Thanks for the confirmation.

69de44d1bb introduced a regression in rc4, reported to the list on August 2, that's still there in rc6. It's also reported on kernel bugzilla as bug #214000. No maintainer response either on-list or to the bug. The commit was general ttm and the original post went to dri-devel and kernel, Jason E. and Daniel V., but all three user reports I've seen so far (two on-list and the bug reporter) are on amdgpu or radeon, so in an effort to at least get a response and hopefully a fix before release, I'm adding the amdgpu/radeon list and maintainers.

The bugzilla report confirmed that CONFIG_DEBUG_FS=y AND CONFIG_DEBUG_FS_ALLOW_ALL=y were *both* required to get a working kernel after that commit. I and I believe the on-list reporter just reverted the commit in question, and kept our CONFIG_DEBUG_FS=n.

Trying again. I apologize if anyone gets this twice but I don't think the first one made it at all (buggy client).