On 7/16/25 3:22 AM, Maxime Ripard wrote:
Hi Mario,
On Mon, Jul 14, 2025 at 04:21:46PM -0500, Mario Limonciello wrote:
From: Mario Limonciello <mario.limonciello@xxxxxxx>
On systems with multiple GPUs there can be uncertainty which GPU is the
primary one used to drive the display at bootup. In order to disambiguate
this add a new sysfs attribute 'boot_display' that uses the output of
video_is_primary_device() to populate whether a PCI device was used for
driving the display.
Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
v7:
* fix lkp failure
* Add tag
v6:
* Only show for the device that is boot display
* Only create after PCI device sysfs files are initialized to ensure
that resources are ready.
v4:
* new patch
---
Documentation/ABI/testing/sysfs-bus-pci | 8 +++++
drivers/pci/pci-sysfs.c | 46 +++++++++++++++++++++++++
2 files changed, 54 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 69f952fffec72..8b455b1a58852 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -612,3 +612,11 @@ Description:
# ls doe_features
0001:01 0001:02 doe_discovery
+
+What: /sys/bus/pci/devices/.../boot_display
+Date: October 2025
+Contact: Linux PCI developers <linux-pci@xxxxxxxxxxxxxxx>
+Description:
+ This file indicates the device was used as a boot
+ display. If the device was used as the boot display, the file
+ will be present and contain "1".
It would probably be a good idea to define what a "boot display" here
is. I get what you mean, but it's pretty vague and could easily be
misunderstood.
Maxime
Here's my proposal for updated text, can you please bikeshed or propose
an alternative?
This file indicates that displays connected to the device were used to
display the boot sequence. If a display connected to the device was
used to display the boot sequence the file will be present and contain "1".
