attributes.
Attributes should be ASCII text files, preferably with only one value
-per file. It is noted that it may not be efficient to contain only
+per file. It is noted that it may not be efficient to contain only one
value per file, so it is socially acceptable to express an array of
values of the same type.
Recall that an attribute should only be exporting one value, or an
array of similar values, so this shouldn't be that expensive.
- This allows userspace to do partial reads and seeks arbitrarily over
- the entire file at will.
+ This allows userspace to do partial reads and forward seeks
+ arbitrarily over the entire file at will. If userspace seeks back to
+ zero or does a pread(2) with an offset of '0' the show() method will
+ be called again, rearmed, to fill the buffer.
- On write(2), sysfs expects the entire buffer to be passed during the
first write. Sysfs then passes the entire buffer to the store()
Other notes:
+- Writing causes the show() method to be rearmed regardless of current
+ file position.
+
- The buffer will always be PAGE_SIZE bytes in length. On i386, this
is 4096.
The sysfs directory arrangement exposes the relationship of kernel
data structures.
-The top level sysfs diretory looks like:
+The top level sysfs directory looks like:
block/
bus/