linux-kernel - Re: Regression: firmware/sysfb.c device path

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Message-ID: <7ca66c39-cbeb-42c6-bfb4-f381b77cf920@suse.de>
Date: Sun, 14 Jul 2024 21:46:30 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Tj <tj.iam.tj@...ton.me>, Marek Olsak <Marek.Olsak@....com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "1075713@...s.debian.org" <1075713@...s.debian.org>
Subject: Re: Regression: firmware/sysfb.c device path

Marek, could this also be the cause of your reported bug?

Am 13.07.24 um 19:20 schrieb Tj:
> The recent commits to add the parent device path broke Debian's kvm based QA workers for testing installer ISOs after a kernel upgrade from v6.8.12 to v6.9.7. For the details:
>
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1075713
>
> It took some time to  track it down since the superficial symptom appeared to involve the QXL driver. It turned out however to be the fbdev driver; specifically the change in the parent device path in sysfs reported between the two kernels:
>
> 6.8.12:
>
> /sys/class/graphics/fb0 -> ../../devices/platform/vesa-framebuffer.0/graphics/fb0
>
> 6.9.7:
>
> /sys/class/graphics/fb0 -> ../../devices/pci0000:00/0000:00:01.0/vesa-framebuffer.0/graphics/fb0
>
> This breaks xserver-xorg-core's libfbdevhw.so because it differentiates code-paths based on whether "devices/pci" is matched in the symlink.
>
> See hw/xfree86/fbdevhw/fbdevhw.c::fbdev_open()
>
> https://gitlab.freedesktop.org/xorg/xserver/-/blob/master/hw/xfree86/fbdevhw/fbdevhw.c?ref_type=heads#L381

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
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