CONFIG_DEBUG_FS
如何在 WSL2 上启用 debugfs
确认下内核是否开启了 debugfs
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| zcat /proc/config.gz | grep CONFIG_DEBUG_FS
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要想使用 debugfs，首先要挂载它到 /sys/kernel/debug
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| mount -t debugfs none /sys/kernel/debug/
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如果想让挂载在系统重启后自动挂载，在 /etc/fstab 加下面一行
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| debugfs /sys/kernel/debug debugfs defaults 0 0
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在添加后，执行 mount -a 命令将看到 /sys/kernel/debug 文件系统的内容
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| $ ls -ld ./* | sort -k 1.2
--w------- 1 root root 0 May 19 17:03 ./clear_warn_once
--w------- 1 root root 0 May 19 17:03 ./split_huge_pages
-r--r--r-- 1 root root 0 May 19 17:03 ./devices_deferred
-r--r--r-- 1 root root 0 May 19 17:03 ./sleep_time
-rw-r--r-- 1 root root 0 May 19 17:03 ./fault_around_bytes
drwx------ 8 root root 0 May 19 17:03 ./tracing
drwxr-xr-x 2 root root 0 May 19 17:03 ./acpi
drwxr-xr-x 2 root root 0 May 19 17:03 ./btt
drwxr-xr-x 2 root root 0 May 19 17:03 ./ceph
drwxr-xr-x 2 root root 0 May 19 17:03 ./clk
drwxr-xr-x 2 root root 0 May 19 17:03 ./device_component
drwxr-xr-x 2 root root 0 May 19 17:03 ./dma_buf
drwxr-xr-x 2 root root 0 May 19 17:03 ./error_injection
drwxr-xr-x 2 root root 0 May 19 17:03 ./extfrag
drwxr-xr-x 2 root root 0 May 19 17:03 ./hid
drwxr-xr-x 2 root root 0 May 19 17:03 ./kprobes
drwxr-xr-x 2 root root 0 May 19 17:03 ./kvm
drwxr-xr-x 2 root root 0 May 19 17:03 ./ramdisk_pages
drwxr-xr-x 2 root root 0 May 19 17:03 ./ras
drwxr-xr-x 2 root root 0 May 19 17:03 ./swiotlb
drwxr-xr-x 2 root root 0 May 19 17:03 ./usb
drwxr-xr-x 2 root root 0 May 19 17:03 ./virtio-ports
drwxr-xr-x 2 root root 0 May 19 17:03 ./x86
drwxr-xr-x 3 root root 0 May 19 17:03 ./dri
drwxr-xr-x 3 root root 0 May 19 17:03 ./sched
drwxr-xr-x 29 root root 0 May 19 17:03 ./block
drwxr-xr-x 35 root root 0 May 19 17:03 ./bdi
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/sys/kernel/debug 目录的权限是 700, 只有 root 用户才能进入，sudo 也不行
CONFIG_DEBUG_ATOMIC_SLEEP
dma_fence_wait_timeout() 会睡眠调用进程直到 fence 被 signaled 或者指定定时器超时。该函数中会调用 might_sleep() 来标识 (annotation) 调用进程可能进入睡眠状态，并打印源文件名和行号，帮助调试。 但只有内核配置了 CONFIG_DEBUG_ATOMIC_SLEEP 才有效，否则 __might_sleep() 是一个空函数。
CONFIG_DRM_USE_DYNAMIC_DEBUG
References
[1] https://access.redhat.com/solutions/5914171