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authorEduard Zingerman <eddyz87@gmail.com>2026-09-04 01:33:23 -0700
committerKumar Kartikeya Dwivedi <memxor@gmail.com>2026-09-04 12:58:04 +0200
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tree95e38e4aaa0a6a78e373148b3d0af4aa2ab3d371 /Documentation/gpu/amdgpu/ptl.rst
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selftests/bpf: Check that JMP32 pointer vs zero jumps are not predictedgrafted
Add jmp32_ptr_vs_zero_jne: the fall-through of the 32-bit compare, which the verifier used to skip, contains an out of bounds map value access, hence w/o the previous patch the program is accepted. See previous patch for detailed description. Reported-by: Nicholas Carlini <npc@anthropic.com> Suggested-by: Nicholas Carlini <npc@anthropic.com> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20260904083325.2083493-6-eddyz87@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
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+=======================================
+Peak Tops Limiter (PTL) sysfs Interface
+=======================================
+
+Overview
+--------
+The Peak Tops Limiter (PTL) sysfs interface enables users to control and
+configure the PTL feature for each GPU individually. All PTL-related
+sysfs files are located under `/sys/class/drm/cardX/device/ptl/`, where
+`X` is the GPU index. Through these files, users can enable or disable
+PTL, set preferred data formats, and query supported formats for each GPU.
+
+PTL sysfs files
+----------------
+The following files are available under `/sys/class/drm/cardX/device/ptl/`:
+
+- `ptl_enable`
+- `ptl_format`
+- `ptl_supported_formats`
+
+PTL Enable/Disable
+------------------
+File: `ptl_enable`
+Type: Read/Write (rw)
+
+Read: Returns the current PTL status as a string: `enabled` if PTL
+is active, or `disabled` if inactive.
+
+Write:
+
+- Write `1` or `enabled` to enable PTL
+- Write `0` or `disabled` to disable PTL
+
+Examples::
+
+ # Query PTL status
+ cat /sys/class/drm/card1/device/ptl/ptl_enable
+ # Output: enabled
+
+ # Enable PTL
+ sudo bash -c "echo 1 > /sys/class/drm/card1/device/ptl/ptl_enable"
+
+ # Disable PTL
+ sudo bash -c "echo 0 > /sys/class/drm/card1/device/ptl/ptl_enable"
+
+PTL Format (Preferred Data Formats)
+-----------------------------------
+File: `ptl_format`
+Type: Read/Write (rw)
+
+Read: Returns the two preferred formats, e.g. `I8,F32`.
+
+Write: Accepts two formats separated by a comma, e.g. `I8,F32`.
+
+- Both formats must be supported and different.
+- If an invalid format is provided (not supported, or both formats are the
+ same), the driver will return "write error: Invalid argument".
+
+Examples::
+
+ # Query PTL formats
+ cat /sys/class/drm/card1/device/ptl/ptl_format
+ # Output: I8,F32
+
+ # Set PTL formats
+ sudo bash -c "echo I8,F32 > /sys/class/drm/card1/device/ptl/ptl_format"
+
+Supported Formats
+-----------------
+File: `ptl_supported_formats`
+Type: Read-only (r)
+
+Read: Returns a comma-separated list of supported formats, e.g.
+`I8,F16,BF16,F32,F64`.
+
+Example::
+
+ # Check supported formats
+ cat /sys/class/drm/card1/device/ptl/ptl_supported_formats
+ # Output: I8,F16,BF16,F32,F64
+
+Behavioral Notes
+----------------
+- PTL formats can only be set when PTL is enabled.
+- If PTL is disabled, `ptl_format` returns `N/A`.
+- Only two formats can be set at a time, and they must be from the supported set and different..
+- All commands support per-GPU targeting.
+- Root permission is required to enable/disable PTL or change formats.
+- If the hardware does not support PTL, the PTL sysfs directory will not
+ be created.
+
+Implementation
+--------------
+The PTL sysfs nodes are implemented in `drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c`.