[lldb-dev] LLDB Process Attach Failed When Waiting

Ryan Lovelett via lldb-dev lldb-dev at lists.llvm.org
Mon Jun 4 05:56:50 PDT 2018


Is there anything I can do to help you implement or test this feature?
Obviously I'm willing to roll-up my sleeves and work on this myself too
if you've become more busy than you expected. That happens to us all and
I completely understand.
Not being able to debug in this manner is blocking me from adding Linux
support to a Swift program. As you might imagine, I'm a little antsy to
get past this so I can start writing some code.
On Thu, May 31, 2018, at 5:08 PM, Greg Clayton wrote:
>> On May 31, 2018, at 12:40 PM, Ryan Lovelett <ryan at lovelett.me> wrote:>> 
>> Well at least there is a little good news. I understood way more of
>> those logs than I thought I did.>> 
>>> So two issues here:
>>> 1 - we need a better error message when vAttachWait returns
>>> unsupported>>> 2 - fix lldb-server to support vAttachWait
>> A few questions.
>> What is the protocol here? Can/should I report the issues at
>> https://bugs.llvm.org/ ? Or is that something that a project member
>> needs to do? Assuming that I can, would this be two seperate issues
>> or one "large" issue?>> 
>> Barring that this is not something someone else might implement
>> better/faster than me. Considering I have zero LLDB development
>> experience is this something that I could tackle?> 
> I didn't realize this functionality was missing in lldb-server. I can
> take a stab at implementing it and see what I can do. Stay tuned.> 
>> On Thu, May 31, 2018, at 3:02 PM, Greg Clayton wrote:
>>> lldb-server claims it doesn't support it:
>>> lldb             <  48> send packet:
>>> $vAttachWait;6c616e677365727665722d7377696674#d6>>> lldb             <   4> read packet: $#00
>>> Returning the empty packet ("$#00") means it is not supported, but
>>> we really should give a better error message than this.>>> 
>>> It isn't that hard to implement. It would be easy to copy the code
>>> that is in debugserver in DNB.cpp in the DNBProcessAttachWait
>>> function. Most of it is probably posix style stuff.>>> 
>>> So two issues here:
>>> 1 - we need a better error message when vAttachWait returns
>>> unsupported>>> 2 - fix lldb-server to support vAttachWait
>>> Greg
>>>> On May 31, 2018, at 11:04 AM, Ryan Lovelett <ryan at lovelett.me>
>>>> wrote:>>>> 
>>>>> It might be a lldb-server issue?
>>>> How would one go about determining this?
>>>> (lldb) log enable -f /tmp/packates.txt gdb-remote packets
>>>> (lldb) process attach --name "<name>" --waitfor
>>>> error: attach failed: lost connection
>>>> Attached the log output. Maybe it'll make more sense to you
>>>> than me.>>>> 
>>>> That escalated quickly. So I've read through that log. I found
>>>> something that says $qVAttachOrWaitSupported#38 with the following
>>>> response being $#00. Perhaps I'm reading too much but is it that
>>>> it's reporting that it is not supported?>>>> 
>>>> Does lldb-server need to be compiled in a certain way to add
>>>> support for attach wait?>>>> 
>>>> On Thu, May 31, 2018, at 1:49 PM, Greg Clayton wrote:
>>>>> Try enabling logging with:
>>>>> (lldb) log enable -f /tmp/packets.txt gdb-remote packets
>>>>> And the try the attach. It might be a lldb-server issue?
>>>>>> On May 31, 2018, at 9:02 AM, Ryan Lovelett via lldb-dev <lldb-
>>>>>> dev at lists.llvm.org> wrote:>>>>>> 
>>>>>> I am attempting to use: process attach --name "<name>" --waitfor>>>>>> 
>>>>>> The problem is that it immediately returns error: attach failed:
>>>>>> lost connection.>>>>>> 
>>>>>> Is this something I can troubleshoot further? Or is this not
>>>>>> supported on Linux?>>>>>> 
>>>>>> -- 
>>>>>> Ryan Lovelett
>>>>>> _______________________________________________
>>>>>> lldb-dev mailing list
>>>>>> lldb-dev at lists.llvm.org
>>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>>>> <packates.txt>

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