[okl4-developer] What does the "STRING_major" mean?

[Guanghui, Cheng]

On Wednesday 22 April 2009 11:24:20 pm Josh Matthews wrote:
> Hi Cheng,
>
> On Tue, April 21, 2009 10:44 pm, Guanghui, Cheng wrote:
> > On Wednesday 22 April 2009 02:07:36 am Josh Matthews wrote:
> >> On Mon, April 20, 2009 10:44 pm, Guanghui, Cheng wrote:
> >> > In the pistachio/include/traceids.h/traceids.h file, there is a enum :
> >> > enum trace_major_ids {
> >> >     EVENT_major                         = 0,
> >> >     STRING_major                        = 1,
> >> >     INTERRUPT_major                     = 2,
> >> >
> >> >     SYSCALL_IPC_major                   = 3,
> >> >     ... ...
> >> > }
> >> >
> >> > I want to know what the STRING means? STRING_IPC or whatever.
> >>
> >> This functionality is all related to the tracebuffers feature. Each
> >> kernel
> >> event is assigned a unique trace identifier in enum trace_ids.
> >> Additionally, each kernel event is assigned to a group in enum
> >> trace_major_ids (as you copied above).
> >>
> >> Calls to tb_log_trace, passing the major (group) identifier and the
> >> event
> >> identifier (and potentially other data), are made by the kernel on the
> >> occurrence of each event (in debug and tracebuffer builds of the kernel
> >> only).
> >>
> >> The major identifier is useful as it allows you to mask out all events
> >> of
> >> particular groups that you are not interested in and focus only on those
> >> groups that you are (see field log_mask in trace_buffer_t, in file
> >> pistachio/include/tracebuffer.h, and see how macro TBUF_RECORD will only
> >> log the event if the bit corresponding to the major number of the event
> >> is
> >> active in the log mask).
> >
> > Thanks for your reply.
> > In the list there are several kinds of trace IDs like this:	event,
> > string, interrupt, 	system call.  I don't know what the string means.
>
> A string event is just a general event that has no other semantics beyond
> some user-defined data that is passed when logging the event.
>
> Check out dump_buffer() in pistachio/kdb/src/tracebuffer.cc - you can see
> how a string event just has its data array printed as a string.
>
> You can use it to log some information about an event in the kernel that
> doesn't fit into any existing defined event or category.
	Thanks a lot.
									Cheng