linux-kernel - Re: [PATCH v9 8/9] fbcon: Use screen info to find primary device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250722143817.GA2783917@bhelgaas>
Date: Tue, 22 Jul 2025 09:38:17 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Mario Limonciello <superm1@...nel.org>
Cc: David Airlie <airlied@...il.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	Simona Vetter <simona@...ll.ch>, Lukas Wunner <lukas@...ner.de>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Woodhouse <dwmw2@...radead.org>,
	Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
	Alex Williamson <alex.williamson@...hat.com>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
	"open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
	open list <linux-kernel@...r.kernel.org>,
	"open list:INTEL IOMMU (VT-d)" <iommu@...ts.linux.dev>,
	"open list:PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
	"open list:VFIO DRIVER" <kvm@...r.kernel.org>,
	"open list:SOUND" <linux-sound@...r.kernel.org>,
	Daniel Dadap <ddadap@...dia.com>,
	Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH v9 8/9] fbcon: Use screen info to find primary device

On Thu, Jul 17, 2025 at 12:38:11PM -0500, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@....com>
> 
> On systems with non VGA GPUs fbcon can't find the primary GPU because
> video_is_primary_device() only checks the VGA arbiter.
> 
> Add a screen info check to video_is_primary_device() so that callers
> can get accurate data on such systems.

This relies on screen_info, which I think is an x86 BIOS-ism.  Isn't
there a UEFI console path?  How does that compare with this?  Is that
relevant or is it something completely different?

>  bool video_is_primary_device(struct device *dev)
>  {
> +#ifdef CONFIG_SCREEN_INFO
> +	struct screen_info *si = &screen_info;
> +#endif
>  	struct pci_dev *pdev;
>  
>  	if (!dev_is_pci(dev))
> @@ -34,7 +38,18 @@ bool video_is_primary_device(struct device *dev)
>  
>  	pdev = to_pci_dev(dev);
>  
> -	return (pdev == vga_default_device());
> +	if (!pci_is_display(pdev))
> +		return false;
> +
> +	if (pdev == vga_default_device())
> +		return true;
> +
> +#ifdef CONFIG_SCREEN_INFO
> +	if (pdev == screen_info_pci_dev(si))
> +		return true;
> +#endif
> +
> +	return false;
>  }
>  EXPORT_SYMBOL(video_is_primary_device);
>  
> -- 
> 2.43.0
>