Public bug reported:
[SRU Justification]
[Impact]
On multi-GPU systems, a VGA-compatible device that is not driving the display
can incorrectly be reported as the primary graphics device through the
boot_display sysfs attribute.
[Fix]
Apply upstream commit 596b3678326d3d1aed7c19423b6746f1ce09688a
("x86/video: Only fall back to vga_default_device() without screen info").
When framebuffer screen information is valid, use it exclusively to identify
the primary device. Fall back to vga_default_device() only when no framebuffer
has been set up.
[Test Plan]
Boot a multi-GPU system and verify that boot_display identifies only the GPU
backing the framebuffer. Verify fallback behavior when no framebuffer has
been initialized.
[Where problems could occur]
The change is limited to primary display-device detection in
arch/x86/video/video-common.c. The main risk is incorrect identification of the
primary GPU on systems with unusual or incomplete framebuffer information.
** Affects: ubuntu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2161036
Title:
[SRU] Fix incorrect boot_display reporting on multi-GPU systems
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