Re: Multiplexed registers and invalidating the register cache

[Orjan Friberg <orjan.friberg@axis.com>]

Andrew Cagney wrote:
> 
> - the frame cache is built on-demand, hence the absence of any explict 
> rebuild call (one characteristic of a frame ID is that it survives frame 
> cache flushes)

In other words, I shouldn't expect to see a whole lot of communication 
with the remote target simply because I flush the frame cache.

> - there shouldn't be separate register and frame flush calls, combining 
> the two into a single observer call is a thing-to-do-today

Ok, let's see if I understand this correctly.  Sorry if I'm asking what 
is (or should be) obvious (I only see observer.exp using this code as of 
now, so it's not clear to me how this is supposed to be used within GDB).

A new event needs to be defined (user_changed_registers(?), taking the 
register number as an argument).  This will give us attach/detach/notify 
functions related to that event.  So, someone needs to attach a 
callback: is this something that should be done in target-specific files?

If so, should targets provide their own callback implementation (which 
flushes the register and frame cache when deemed appropriate), or should 
there be a predefined function that the target-specific file simply 
references when attaching the callback?

In addition, someone needs to notify that the event has happened, but I 
assume these notifications should be inserted at the same places that 
register_changed_hook is called for GUI purposes.

Anything I missed or misunderstood?

-- 
Orjan Friberg
Axis Communications