[lldb-dev] LLDB sends continue right after connection (gdb-remote)

[Benjamin Kemper]

Hi Greg,

Thanks, this seems like a very plausible reason.

Two questions:
1. Do  I need to implement all the stop reply packet extensions (In the
description it says that they are good for performance but no necessary) or
just qThreadStopInfo?

2. I've looked at the ? command in my logs and saw that I'm receiving
something different than T00, is this value Ok or also bad?

The log:
<   5> send packet: $?#3f
size_t
GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock(StringExtractorGDBRemote
&, uint32_t): Read (buffer, (sizeof(buffer), timeout_usec = 0xf4240, status
= success, error = (null)) => bytes_read = 1
<   1> read packet: +
size_t
GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock(StringExtractorGDBRemote
&, uint32_t): Read (buffer, (sizeof(buffer), timeout_usec = 0xf4240, status
= success, error = (null)) => bytes_read = 52
<  52> read packet: $T0206:0*,;07:f08a5851ff7f0* ;10:2880276eff7f0* ;#67
<   1> send packet: +

Thanks for the help,
Benjamin.


On Tue, Jan 22, 2013 at 7:53 PM, Greg Clayton <gclayton at apple.com> wrote:

> I believe we have a bug where if you attach and the stop reply packet that
> we send immediately after the attach (the '?' packet) comes back with a T00
> (meaning the thread stopped with signal 0, or no signal), we end up
> resuming the process. We normally get a T11 (SIGSTOP) when we first attach
> on MacOSX. This gives LLDB a reason for why the process stopped. It is also
> helpful if you add the stop reply packet extensions we have documented in
> the "lldb-gdb-remote.txt" file in our SVN repository:
>
> svn cat
> http://llvm.org/svn/llvm-project/lldb/trunk/docs/lldb-gdb-remote.txt
>
> See the section labeled "Stop reply packet extensions". The standard stop
> reply packet is really UNIX centric and it assumes every stop reason can be
> explained by a signal. We extended the contents of the key/value pairs that
> are returned to provide more complete information.
>
> Can you enable GDB packet logging and send me the output? I will be able
> to tell more from the log.
>
> To enable this logging:
>
> (lldb) log enable -f /tmp/packets.txt  gdb-remote packets
> (lldb) … < connect to remote process > …
> (lldb) quit
>
> Then attach and send the packet.txt file.
>
> Greg
>
> On Jan 22, 2013, at 6:55 AM, Benjamin Kemper <kemperbenny at gmail.com>
> wrote:
>
> > ProcessGDBRemote::UpdateThreadList (pid = 1799)
> > 0x7fe2aa2268b0: ThreadGDBRemote::ThreadGDBRemote (pid = 1799, tid =
> 0x0707)
> > <  22> send packet: $qThreadStopInfo707#99
> > size_t
> GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock(StringExtractorGDBRemote
> &, uint32_t): Read (buffer, (sizeof(buffer), timeout_usec = 0xf4240, status
> = success, error = (null)) => bytes_read = 1
> > <   1> read packet: +
> > size_t
> GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock(StringExtractorGDBRemote
> &, uint32_t): Read (buffer, (sizeof(buffer), timeout_usec = 0xf4240, status
> = success, error = (null)) => bytes_read = 4
> > <   4> read packet: $#00
> > <   1> send packet: +
> > error: failed to get response for 'qThreadStopInfo707'
> > ProcessGDBRemote::Resume()
> > ProcessGDBRemote::AsyncThread (arg = 0x7fe2ab00d000, pid = 1799) Got an
> event of type: 1...
> > ProcessGDBRemote::AsyncThread (arg = 0x7fe2ab00d000, pid = 1799) got
> eBroadcastBitAsyncContinue: vCont;c:0707
> > GDBRemoteCommunicationClient::SendContinuePacketAndWaitForResponse ()
> > GDBRemoteCommunicationClient::SendContinuePacketAndWaitForResponse ()
> sending continue packet: vCont;c:0707
> > <  16> send packet: $vCont;c:0707#b0
> > size_t
> GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock(StringExtractorGDBRemote
> &, uint32_t): Read (buffer, (sizeof(buffer), timeout_usec = 0xf4240, status
> = success, error = (null)) => bytes_read = 1
> > <   1> read packet: +
> > GDBRemoteCommunicationClient::SendContinuePacketAndWaitForResponse ()
> WaitForPacket(vCont;c:0707)
> > size_t
> GDBRemoteCommunication::WaitForPacketWithTimeoutMicroSecondsNoLock(StringExtractorGDBRemote
> &, uint32_t): Read (buffer, (sizeof(buffer), timeout_usec = 0xffffffff,
> status = success, error = (null)) => bytes_read = 7
> > <   7> read packet: $W00#b7
> > <   1> send packet: +
> > GDBRemoteCommunicationClient::SendContinuePacketAndWaitForResponse ()
> got packet: W00
> > GDBRemoteCommunicationClient::SendContinuePacketAndWaitForResponse () =>
> exited
> > ProcessGDBRemote::AsyncThread (arg = 0x7fe2ab00d000, pid = 1799) thread
> exiting...
> >
>
>
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