Hello everyone, I am going through Documentation/filesystems/sysfs.rst. It says that sysfs allocates a buffer of size PAGE_SIZE and passes it to the show/store functions of the attribute. On read(), the show() method should fill the entire buffer[0]. The document also says that sysfs_emit() and sysfs_emit_at() are the preferred function calls in show() function when formatting the value to be returned to the user space [1]. I checked the sysfs_emit() function definition. sysfs_emit() -> vscnprintf() -> vsnprintf() is the function series. (-> = calls) In the vsnprintf() function, i found that only in the case of (start + size > end) the buffer is completely filled, in the other case, that's not the case [2]. Isn't this contradictory to what the sysfs.rst says? (that entire buffer should be filled) Can you please help me understand what i am missing here? Thank you for your time. Cheers, ymdatta. [0]: https://elixir.bootlin.com/linux/latest/source/Documentation/filesystems/sysfs.rst#L214 [1]: https://elixir.bootlin.com/linux/latest/source/Documentation/filesystems/sysfs.rst#L246 [2]: https://elixir.bootlin.com/linux/latest/source/lib/vsprintf.c#L2689 _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
