[lldb-dev] LLDB Process Attach Failed When Waiting

[Greg Clayton via lldb-dev]

> 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/ <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 <mailto: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 <mailto: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 <mailto:lldb-dev at lists.llvm.org>
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>>> <packates.txt>

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