Skip to content

Embedded Linux Learning

sysfs attributes

Sysfs Attributes¶

Purpose¶

Sysfs exposes device configuration and status as text-based files under /sys.

Common Callback Pattern¶

static ssize_t value_show(struct device *dev,
                          struct device_attribute *attr,
                          char *buf)
{
    return sysfs_emit(buf, "%d\n", value);
}

static ssize_t value_store(struct device *dev,
                           struct device_attribute *attr,
                           const char *buf,
                           size_t count)
{
    return count;
}

Good Use Cases¶

Use Case	Suitable for sysfs?
Simple status value	Yes
Simple configuration value	Yes
Streaming data	No
Complex binary command	Usually no

Common Pitfalls¶

Warning

Sysfs files should expose one value or one logical setting per file.

Warning

Sysfs is not intended for high-rate event streaming.