[lttng-dev] UST tracing problem on ARM/Android

[Charles Briere]

Hello world,

I've been running in some inssues lately with UST on ARM/Android. Using
the following to configure my session, I enable every ust event.

lttng create
lttng enable-event -ua

Although, when a tracepoint is called, its state ( struct
lttng_ust_tracepoint -> state) is 0. 

My understanding of the whole registration process is limited, so the
following reasoning is probably flawed, so please correct me if that
happens. 

I found out, that when registering the library
(tracepoint_register_lib), callsite_table is populated. But later on
when it comes to register the probes (lttng_prove_register),
callsite_table 's address is different and the list is empty. As a
result, when tracepoint_sync_callsite() is called, set_tracepoint() is
never executed as looping through an empty list. 

What I don't understand in here, is that the callsite_table pointer is
not the same during the lib registration and probe registration. Both
are ran sequentially in the same thread and I can't figure what other
operation could affect the variable. Any hint/help would be much
appreciated.

Thanks,
Charles