[lldb] Document QSetDetachOnError packet

[fdeazeve]

Summary

The packet was introduced in 106d02866d4d54b09c08e6a12915dba58e709294.

[jingham]

LGTM, thanks for adding this.

[jasonmolenda]

LGTM. Not really the place for it, but the idea is: if lldb launched a process, when lldb quits, the inferior process should be killed. But if lldb attached to a running process, when lldb quits, the inferior process should be detached from & left running. debugserver often can't tell the difference between these (when you run a process on a local system, lldb actually does the posix_spawn and then tells debugserver to attach to it).

[fdeazeve]

In D136958#3896820, @jasonmolenda wrote:

debugserver often can't tell the difference between these (when you run a process on a local system, lldb actually does the posix_spawn and then tells debugserver to attach to it).

That makes a lot of sense!

lldb/docs/lldb-gdb-remote.txt

 "socket_name": <the name of the socket to connect> (optional)
 
 Example packet:
 [
     { "port": 1234 },
     { "port": 5432 },
     { "socket_name": "foo" }
 ]
+
+//----------------------------------------------------------------------
+// "QSetDetachOnError"
+//
+// BRIEF
+//  Sets what the server should do when the communication channel with LLDB
+//  goes down. Either kill the inferior process (0) or remove breakpoints and
+//  detach (1).
+//
+// PRIORITY TO IMPLEMENT
+//  Low. Only required if the target wants to keep the inferior process alive
+//  when the communication channel goes down.
+//----------------------------------------------------------------------
+
+The data in this packet is a single a character, which should be '0' if the
+inferior process should be killed, or '1' if the server should remove all
+breakpoints and detach from the inferior.