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

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Date:   Tue, 3 Aug 2021 08:54:18 +0200
From:   Mikael Pettersson <mikpelinux@...il.com>
To:     Duncan <j.duncan@....net>
Cc:     Daniel Vetter <daniel.vetter@...ll.ch>,
        dri-devel@...ts.freedesktop.org,
        Jason Ekstrand <jason@...kstrand.net>,
        Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: Re: [BISECTED] 5.14.0-rc4 broke drm/ttm when !CONFIG_DEBUG_FS

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

Yes, I have the Fedora boot splash enabled.

> > 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.