[lldb-dev] Launching the program through 'gdb-remote' process plugin
chansarav
chansarav at gmail.com
Fri Aug 23 07:56:09 PDT 2013
> IS this what is going on? If so, just give lldb the executable file:
No. I initiated lldb with the arguments "--arch vliw-unknown-unknown
workplace/app.elf". But I haven't mentioned in my previous mail.
$lldb
(lldb) log enable gdb-remote packets
(lldb) target create --arch vliw-unknown-unknown workplace/app.elf
Current executable set to 'workplace/app.elf' (vliw).
(lldb) process connect --plugin gdb-remote connect://localhost:51000
< 1> send packet: +
history[1] tid=0xb1cbe9d0 < 1> send packet: +
< 19> send packet: $QStartNoAckMode#b0
< 1> read packet: +
< 4> read packet: $#00
< 1> send packet: +
< 26> send packet: $QThreadSuffixSupported#e4
< 1> read packet: +
< 4> read packet: $#00
< 1> send packet: +
< 27> send packet: $QListThreadsInStopReply#21
< 1> read packet: +
< 4> read packet: $#00
< 1> send packet: +
< 13> send packet: $qHostInfo#9b
< 1> read packet: +
< 84> read packet:
$cputype:201;cpusubtype:-2;ostype:unknown;vendor:unknown;endian:little;ptrsize:4;#90
< 1> send packet: +
< 10> send packet: $vCont?#49
< 1> read packet: +
< 15> read packet: $vCont[;c;s]#0e
< 1> send packet: +
< 27> send packet: $qVAttachOrWaitSupported#38
< 1> read packet: +
< 4> read packet: $#00
< 1> send packet: +
< 6> send packet: $qC#b4
< 1> read packet: +
< 7> read packet: $QC0#c4
< 1> send packet: +
(lldb) process launch
I debugged lldb to check the "ProcessGDBRemote::DoLaunch()" method. But the
execution didn't reach this function for the above said communication.
Actually after the "process connect" the state is set to "eStateConnected".
So the "process launch" should call the "DoLaunch()" method of "gdb-remote"
process plugin. But lldb hangs on the last line of the following code snip.
(snip start)
if (error.Success())
{
const char *archname =
exe_module->GetArchitecture().GetArchitectureName();
//result.AppendMessageWithFormat ("Process %llu launched: '%s' (%s)\n",
process->GetID(), filename, archname);
result.SetDidChangeProcessState (true);
if (m_options.launch_info.GetFlags().Test(eLaunchFlagStopAtEntry) ==
false)
{
result.SetStatus (eReturnStatusSuccessContinuingNoResult);
StateType state = process->WaitForProcessToStop (NULL);
(snip end)
file: lldb/source/Commands/CommandObjectProcess.cpp
method: CommandObjectProcessLaunch::DoExecute()
On Thu, Aug 22, 2013 at 10:21 PM, Greg Clayton <gclayton at apple.com> wrote:
> You probably didn't give LLDB a file with "target create". If you look at
> the "ProcessGDBRemote::DoLaunch (...)" function, it gets the object file
> from the target's executable module to ensure there is something to launch:
>
>
> ObjectFile * object_file = exe_module->GetObjectFile();
> if (object_file)
> {
>
> ... send 'A' packet
>
> }
>
>
> It really doesn't make sense to run a program that has no executable and
> has no arguments. If you have a simulator that is debugging something
> already, then you must reply with a non-zero PID to the "qC" packet. Below
> your packets were:
>
> < 6> send packet: $qC#b4
> < 1> read packet: +
> < 7> read packet: $QC0#c4
> < 1> send packet: +
>
> This is telling us, we are connected, but aren't debugging anything yet.
> There is a bug in LLDB right now if this is the case where we aren't
> propagating an error back from Process::Launch() correctly stating the 'A'
> packet can't be sent without a valid executable.
>
> IS this what is going on? If so, just give lldb the executable file:
>
> (lldb) target create --arch <ARCH> /path/to/local/copy/of/sim/exe/a.out
> (lldb) process connect --plugin gdb-remote connect://localhost:51000
>
> On Aug 21, 2013, at 10:14 PM, chansarav <chansarav at gmail.com> wrote:
>
> > Thanks for the reply.
> >
> > I enabled the packet logging in LLDB.
> >
> > (lldb) log enable gdb-remote packets
> > (lldb) process connect --plugin gdb-remote connect://localhost:51000
> > < 1> send packet: +
> > history[1] tid=0xb1d819d0 < 1> send packet: +
> > < 26> send packet: $QThreadSuffixSupported#e4
> > < 1> read packet: +
> > < 4> read packet: $#00
> > < 1> send packet: +
> > < 27> send packet: $QListThreadsInStopReply#21
> > < 1> read packet: +
> > < 7> read packet: $E01#a6
> > < 1> send packet: +
> > < 10> send packet: $vCont?#49
> > < 1> read packet: +
> > < 15> read packet: $vCont[;c;s]#0e
> > < 1> send packet: +
> > < 27> send packet: $qVAttachOrWaitSupported#38
> > < 1> read packet: +
> >
> > < 6> send packet: $qC#b4
> > < 1> read packet: +
> > < 7> read packet: $QC0#c4
> > < 1> send packet: +
> > (lldb) run
> >
> > After this lldb just hangs. lldb doesn't send any packet after the 'run'
> command. I debugged by inserting a breakpoint in lldb's code which sends
> the 'A' packet. And that breakpoint was not hit.
> >
> >
> >
> > On Wed, Aug 21, 2013 at 10:31 PM, Greg Clayton <gclayton at apple.com>
> wrote:
> > The "process launch" command should send the 'A' packet, and it is
> waiting for a stop reply response from the 'A' packet. Try enabling the
> packet logging in LLDB:
> >
> > (lldb) log enable gdb-remote packets
> > (lldb) process connect ...
> > (lldb) run
> >
> > My guess is that the 'A' packet isn't responding with a stop reply
> packet.
> >
> > On Aug 21, 2013, at 7:47 AM, chansarav <chansarav at gmail.com> wrote:
> >
> > > Hi,
> > >
> > > I am connecting lldb with my simulator through 'gdb-remote' process
> plugin. After extablishing the connection, I want to issue the 'process
> launch' command in lldb which should send the arguments packet 'A' to
> simulator asking it to launch the program.
> > >
> > > I am facing the problem while issuing the 'process launch' command in
> lldb. When I give the 'process launch' command, lldb hangs and there is no
> communication with simulator. When I debugged with gdb, I got the backtrace
> as follows:
> > >
> > > #2 0xb6703a6f in lldb_private::Condition::Wait (this=0x8077dac,
> mutex=..., abstime=0x0, timed_out=0xbfffaa9f) at
> /home/chandra/llvm-3.1/tools/lldb/source/Host/common/Condition.cpp:92
> > > #3 0xb662768d in lldb_private::Predicate<bool>::WaitForValueEqualTo
> (this=0x8077d90, value=true, abstime=0x0, timed_out=0xbfffaa9f) at
> /home/chandra/llvm-3.1/tools/lldb/source/Core/../../include/lldb/Host/Predicate.h:317
> > > #4 0xb662b03f in lldb_private::Listener::WaitForEventsInternal
> (this=0x8077d3c, timeout=0x0, broadcaster=0xadb0179c,
> broadcaster_names=0x0, num_broadcaster_names=0, event_type_mask=3,
> event_sp=...) at
> /home/chandra/llvm-3.1/tools/lldb/source/Core/Listener.cpp:409
> > > #5 0xb662b1f7 in
> lldb_private::Listener::WaitForEventForBroadcasterWithType (this=0x8077d3c,
> timeout=0x0, broadcaster=0xadb0179c, event_type_mask=3, event_sp=...) at
> /home/chandra/llvm-3.1/tools/lldb/source/Core/Listener.cpp:440
> > > #6 0xb69421ec in lldb_private::Process::WaitForStateChangedEvents
> (this=0xadb01788, timeout=0x0, event_sp=...) at
> /home/chandra/llvm-3.1/tools/lldb/source/Target/Process.cpp:1069
> > > #7 0xb6941f2c in lldb_private::Process::WaitForProcessToStop
> (this=0xadb01788, timeout=0x0) at
> /home/chandra/llvm-3.1/tools/lldb/source/Target/Process.cpp:977
> > > #8 0xb6587d98 in CommandObjectProcessLaunch::DoExecute
> (this=0x80813d0, launch_args=..., result=...) at
> /home/chandra/llvm-3.1/tools/lldb/source/Commands/CommandObjectProcess.cpp:220
> > > #9 0xb672c999 in lldb_private::CommandObjectParsed::Execute
> (this=0x80813d0, args_string=0xb4d667bc "", result=...) at
> /home/chandra/llvm-3.1/tools/lldb/source/Interpreter/CommandObject.cpp:856
> > > #10 0xb67215d3 in lldb_private::CommandInterpreter::HandleCommand
> (this=0x8077fc8, command_line=0x883a614 "process launch",
> lazy_add_to_history=lldb_private::eLazyBoolYes, result=...,
> > > override_context=0x0, repeat_on_empty_command=true,
> no_context_switching=false) at
> /home/chandra/llvm-3.1/tools/lldb/source/Interpreter/CommandInterpreter.cpp:1571
> > > #11 0xb64e0ced in lldb::SBCommandInterpreter::HandleCommand
> (this=0xbfffc2cc, command_line=0x883a614 "process launch", result=...,
> add_to_history=true) at
> /home/chandra/llvm-3.1/tools/lldb/source/API/SBCommandInterpreter.cpp:97
> > > #12 0x0805a103 in Driver::HandleIOEvent (this=0xbfffec7c, event=...)
> at /home/chandra/llvm-3.1/tools/lldb/tools/driver/Driver.cpp:996
> > > #13 0x0805b516 in Driver::MainLoop (this=0xbfffec7c) at
> /home/chandra/llvm-3.1/tools/lldb/tools/driver/Driver.cpp:1430
> > > #14 0x0805bbf2 in main (argc=4, argv=0xbfffede4, envp=0xbfffedf8) at
> /home/chandra/llvm-3.1/tools/lldb/tools/driver/Driver.cpp:1562
> > >
> > > Though I am analyzing on this, Can someone help me in finding out what
> goes wrong while trying to launch a program in simulator through
> 'gdb-remote' process plugin?
> > >
> > >
> > > Following is the communication between lldb and simulator for the
> "process connect --plugin gdb-remote connect://localhost:51000" command.
> > >
> > > Send Packet: QStartNoAckMode: 15 chars
> > > Read Packet:
> > > Send Packet: QThreadSuffixSupported: 22 chars
> > > Read Packet:
> > > Send Packet: QListThreadsInStopReply: 23 chars
> > > Read Packet: E01
> > > Send Packet: qHostInfo: 9 chars
> > > Read Packet:
> cputype:201;cpusubtype:-2;ostype:unknown;vendor:unknown;endian:little;ptrsize:4;
> > > Send Packet: vCont?: 6 chars
> > > Read Packet: vCont[;c;s]
> > > Send Packet: qVAttachOrWaitSupported: 23 chars
> > > Read Packet:
> > > Send Packet: qC: 2 chars
> > > Read Packet: QC0
> > >
> > > LLDB sets the status as connected after this communication.
> > > (snip start)
> > > if (pid == LLDB_INVALID_PROCESS_ID)
> > > {
> > > // We don't have a valid process ID, so note that we are
> connected
> > > // and could now request to launch or attach, or get remote
> process
> > > // listings...
> > > SetPrivateState (eStateConnected);
> > > }
> > > (snip end)
> > > function: ProcessGDBRemote::DoConnectRemote ()
> > >
> > > Thanks,
> > > Chandra Kumar R.
> > > _______________________________________________
> > > lldb-dev mailing list
> > > lldb-dev at cs.uiuc.edu
> > > http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
> >
> >
>
>
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