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# This script collects the MMIO trace during initialization of GPU driver.
# Before running this, we need to disable the drm module in use.
# For AMD GPUs do either:
#     echo 'blacklist amdgpu' >> /etc/modprobe.d/blacklist.conf
# or
#     add 'modprobe.blacklist=amdgpu' to your kernel command
# And then reboot.

# First load the drm_kms_helper with fbdev_emulation=0
modprobe drm_kms_helper fbdev_emulation=0

# Path to store the trace
TRACE_PATH="MMIO.trace"

# Choose propoer size to make sure you won’t miss any events
BUFFER_SIZE=8000

DRM_MODULE="amdgpu"
DRM_MODULE_ARGS="ip_block_mask=0xff"

# Setup MMIO tracer
echo $BUFFER_SIZE > /sys/kernel/debug/tracing/buffer_size_kb
echo mmiotrace > /sys/kernel/debug/tracing/current_tracer

# Re-direct the output to a file, process in background
cat /sys/kernel/debug/tracing/trace_pipe > $TRACE_PATH &
# Save the process ID, as we need to kill it later on
PID=$!

# Insert the module, start driver initialization
echo "Running: modprobe -v $DRM_MODULE $DRM_MODULE_ARGS"
modprobe -v $DRM_MODULE $DRM_MODULE_ARGS

# Kill the background process after module is loaded
kill $PID