Re: [PATCH v2] x86/video: Preserve the default VGA fallback for legacy modes

[sashiko-bot@kernel.org]

> Commit 596b3678326d ("x86/video: Only fall back to vga_default_device()
> without screen info") made video_is_primary_device() rely exclusively
> on screen_info resources whenever any are available.
> 
> However, screen_info_resources() also returns legacy I/O and memory
> ranges for VGA text modes. These ranges are not PCI BARs, so
> pci_find_resource() does not find them and the default VGA fallback is
> skipped. As a result, no device is primary in VGA text mode.
> 
> On a SeaBIOS QEMU guest with bochs and VKMS, the boot VGA (bochs) loses
> its DRM boot_display attribute. VKMS registers fb0 and bochs registers
> fb1. VKMS is not a PCI device, so it is not primary either. With no
> primary device, fbcon keeps the console on fb0 and never remaps it to
> bochs. This can be checked with:
> 
> [ ... ]
> Fixes: 596b3678326d ("x86/video: Only fall back to vga_default_device() without screen info")
> Cc: stable@vger.kernel.org
> Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Hengyu Liang <hengyul@cs.unc.edu>

Sashiko has reviewed this patch and found no issues.

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