Re: questions on CONFIG_PPC_ADV_DEBUG_REGS, DBCR0_BRT, and DBCR0_ACTIVE_EVENTS

[shiva7 <sivasakthi7@outlook.com>]

Thanks again Scott.

/> Any idea whether the DBCR0 BRT bit actually works(??), 

> Do you have reason to believe that it might not? /

I'm facing a strange problem which was not there on server processor. Let me
try to give brief flow.

Server :

Set BE bit (thru system call or sigreturn) for specific thread -> for every
branch -> trace exception -> Normal exception prolog (STD_EXCEPTION_COMMON)
SRR0 and SRR1

Embedded/BOOKE:

Set DE & BRT bit (thru system call or sigreturn) for specific thread -> for
every branch taken -> Debug exception -> DEBUG_DEBUG prolog ->
return_dbg_except DSRR0 & DSRR1

In server case, able to capture the branches as expected, but wherein BOOKE
though branch taken exception are generated, at the certain stage (mostly
after turn on BRT & DE bit)  user process is deviated (not taking the same
flow as like server) and leading to different corruption/unexpected
behavior.

/> And also, anything special required for "server" family application code 
> porting here ?? as because in server family the trace exception used to
> viz 
> NORMAL exception proglog and uses SRR0 and SRR1 but in this ISA/embedded 
> case have dedicated DEBUG_DEBUG prolog and dedicated registers DSRR0 and 
> DSRR1. 

> IIRC the branch taken mechanism does have different semantics than the 
> equivalent mechanism on server.  You can find discussion of this in the 
> archives. :-) /

Most of the discussions so far I have surfed are related to branch
taken/fall through(not taken) semantics related. But, in general, if I have
an application running on server where tracing was based on BE bit and same
can run on e500mc with DE & BRT combination?


Thanks In Advance.



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