驅動程式 - Linux Device Driver(LDD) - 解決/sys/kernel/debug/沒有內容的問題

參考資訊：
https://docs.kernel.org/trace/debugging.html

~ # ls /sys/kernel/debug/

~ # mount -t debugfs debugfs /sys/kernel/debug/

~ # ls /sys/kernel/debug/
    asoc                extfrag             regmap
    bcm7271-uart        fault_around_bytes  regulator
    bdi                 gpio                remoteproc
    block               hid                 slab
    clear_warn_once     hns3                sleep_time
    clk                 iio                 split_huge_pages
    debug_enabled       interconnect        suspend_stats
    devfreq             megaraid_sas        swiotlb
    device_component    memblock            tracing
    devices_deferred    mtd                 ufshcd
    dma_buf             opp                 ulpi
    dma_pools           pinctrl             usb
    dmaengine           pm_genpd            virtio-ports
    dpaa2-eth           psci                wakeup_sources
    dynamic_debug       pwm
    energy_model        ras