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73c5a25306
Add a new configfs boolean attribute 'enable_multi_queue' that lets an
administrator force-disable multi-queue support on a device before it
binds to the driver. The attribute defaults to true (use the platform
hardware capability as-is); writing 0 force-disables multi-queue. This
is intended for debugging and for validating non-multi-queue code paths
on hardware that would otherwise expose multi-queue.
The override disables multi-queue at two levels:
- UAPI: In alloc_primary_gt(), clear
gt->info.multi_queue_engine_class_mask on the primary GT so that
xe_gt_supports_multi_queue() returns false and attempts to create
a multi-queue group via DRM_XE_EXEC_QUEUE_SET_PROPERTY_MULTI_GROUP
are rejected.
- GuC: In guc_ctl_feature_flags(), set the GUC_CTL_DISABLE_MULTI_QUEUE
(BIT(24)) init-params bit on GuC firmware older than 70.66. On GuC
firmware 70.66 and above, guc_waklv_init() emits the new
GUC_FEATURE_KLV_DISABLE_MULTI_QUEUE Feature KLV (0x5001) via the ADS
WA/Feature KLV buffer instead. Feature KLVs share the WA KLV buffer.
The attribute is rejected after the device has been bound, so it only
takes effect during probe:
# echo 0 > /sys/kernel/config/xe/0000:03:00.0/enable_multi_queue
# echo 0000:03:00.0 > /sys/bus/pci/drivers/xe/bind
v2: Add log for multi-queue disabled. (Niranjana)
v3: Rename attribute to enable_multi_queue with default true. (Stuart &&
Niranjana)
v4: rebase.
Assisted-by: Claude:claude-opus-4.7
Cc: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
Link: https://patch.msgid.link/20260709200822.3257825-1-shuicheng.lin@intel.com
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
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