linux-kernel - Re: [BISECTED] 5.14.0-rc4 broke drm/ttm when !CONFIG_DEBUG

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Date:   Mon, 2 Aug 2021 11:29:04 -0700
From:   Duncan <j.duncan@....net>
To:     mikpelinux@...il.com
Cc:     daniel.vetter@...ll.ch, dri-devel@...ts.freedesktop.org,
        jason@...kstrand.net, linux-kernel@...r.kernel.org
Subject: Re: [BISECTED] 5.14.0-rc4 broke drm/ttm when !CONFIG_DEBUG_FS

[Not subscribed so please CC me.  Manual quoting after using lore's
in-reply-to functionality.  First time doing that so hope I got it
right.]

Mikael Pettersson <mikpelinux@...il.com> 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
system.

> 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.

-- 
Duncan - HTML messages treated as spam
"They that can give up essential liberty to obtain a little
temporary safety, deserve neither liberty nor safety."
Benjamin Franklin