[lldb-dev] LLDB for bare-iron targets lacking support for qC /qfThreadInfo packet

Jaydeep Patil via lldb-dev lldb-dev at lists.llvm.org
Sun Aug 23 23:51:26 PDT 2015

Hi Greg,

The '?' packet always returns 'S05'. There is no thread information available in any of the packets.


-----Original Message-----
From: Greg Clayton [mailto:clayborg at gmail.com] 
Sent: 21 August 2015 PM 09:43
To: Jaydeep Patil
Cc: lldb-dev at lists.llvm.org
Subject: Re: LLDB for bare-iron targets lacking support for qC /qfThreadInfo packet

One option is to send a ? packet to get a stop reply packet back. The stop reply should contain a "thread:XXXX;" key/value pair and you could just make the pid == tid == XXXX. We currently try these in the order below:

1 - qProcessInfo 
2 - qC
3 - qfThreadInfo

Now we could add a fourth:

4 - ?

> On Aug 21, 2015, at 12:23 AM, Jaydeep Patil <jaydeep.patil at imgtec.com> wrote:
> Hi,
> The gdb-stub running on a MIPS bare-iron board lacks support for qC /qfThreadInfo packet.  Once the LLDB is connected to the target it cannot proceed further as there is no process and/or thread information available from the target. However GDB is able to debug the application as it ignores the output of qC /qfThreadInfo packet if they are not supported. GDB assumes that a process/thread X is available for debugging.
> Is there any way in LLDB to support such bare-iron targets where qC /qfThreadInfo packets are not supported?
> Regards,
> Jaydeep

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