[lldb-dev] strange behaviour at lldb cmd line

[Matthew Gardiner]

Greg Clayton wrote:
> As soon as we attach with any GDB server, we expect one of two things:
> 1 - a process and all its threads are stopped. the $? packet should respond with any thread that has a stop reason _or_ if no threads have a stop reason, then report a $T packet for the first thread. You can probably respond with $T00 if there is no real signal or reason the thread stopped. Some debuggers like to respond with $T05 (SIGTRAP), but I would rather we don't lie and report a bogus SIGTRAP signal and tell the truth ($T00 or no signal).
> 2 - there is no process which means qProcessInfo respond with an invalid value or error, or for backward compatibility qC responds with an invalid value. This lets us know we don't have a process and no $? should be issued.

Hi Greg,

I appreciate this question may be slightly off-topic, but you mentioned 
that on attaching to a GDB server you expect "a process and all it's 
threads are stopped" (or no process).

Does the concept of a non-invasive attach exist in lldb? By that I mean 
can you attach to a process without stopping it.

We have this feature in our current debugger, in additional to 
permitting memory and register reads for certain areas of our chips, it 
may useful to a developer to inspect whether a device is "still running".

I've also observed that the Microsoft Visual Studio debugger also 
permits attach onto a running process, without it's interruption.

Is such a feature achievable using lldb via it's "target" or remoting 
commands?

thanks
Matt



Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom
More information can be found at www.csr.com. Keep up to date with CSR on our technical blog, www.csr.com/blog, CSR people blog, www.csr.com/people, YouTube, www.youtube.com/user/CSRplc, Facebook, www.facebook.com/pages/CSR/191038434253534, or follow us on Twitter at www.twitter.com/CSR_plc.
New for 2014, you can now access the wide range of products powered by aptX at www.aptx.com.