What Should sysfs, debugfs, and procfs Expose?
Linux drivers often expose information through text files in addition to /dev/xxx and ioctl:
/sys/...
/sys/kernel/debug/...
/proc/...
They all support cat and echo, so it is tempting to place state, configuration, debug knobs, and statistics wherever convenient. That convenience becomes interface debt: test scripts depend on debugfs, product applications parse procfs, sysfs formats cannot be changed, and field tools do not know which interface is stable.
A practical boundary is:
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