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From: Simon Marchi <simark@simark.ca>
To: Bill Messmer <wmessmer@microsoft.com>,
	"gdb@sourceware.org" <gdb@sourceware.org>
Subject: Re: Issues With Thread Events In User Mode GDBServer
Date: Sun, 11 Sep 2022 14:55:40 -0400	[thread overview]
Message-ID: <c9fd1e43-539f-3af9-8314-be78d4c7ab2a@simark.ca> (raw)
In-Reply-To: <MN2PR21MB14398C0638256C6DD545FA7CC4439@MN2PR21MB1439.namprd21.prod.outlook.com>



On 2022-09-09 16:04, Bill Messmer via Gdb wrote:
> Folks,
> 
> Apologies if this is the wrong mailing list to ask a question regarding GDBServer / RSP and a potential bug.
> 
> I have been working on new extensibility API surfaces for the Windows platform debuggers that allow folks to write plug-ins that can connect those debugging tools to a variety of new targets including ones that are not Windows based.  We've had the ability to do this for post-mortem targets for some time and are, of late, working to expand that API surface to various forms of live targets.
> 
> As proof of concept for the API surface, I've been experimenting with writing such a plug-in to connect to the standard user mode GDBServer for Linux.  A few things I'll note:
> 
> 
>   1.  When thread events are enabled on the server via a QThreadEvents:1, GDBServer immediately crashes on any thread exit in "resume" on a NULL deref of current_thread.
> 
> 
> 
>   1.  I tried a quick patch here (adding "cs.last_status.kind() != TARGET_WAITKIND_THREAD_EXITED") to the set of conditions that won't set "current_thread->last_status" and the wXXX thread exit packets get sent; however, regardless of whether the target is in non-stop mode or not, the process is STILL RUNNING at the time the server sends the "wXXX" packet.
> 
> 
> Am I missing something with GDBServer and thread events or is this just not well supported...?  The process seems to be stopped at the point that a thread creation event gets sent...  but not for a thread exit...  I assume that's a bug somewhere in GDBServer...?  Or am I misreading the docs at https://sourceware.org/gdb/onlinedocs/gdb/General-Query-Packets.html...?  Is there some alternate means by which thread create/exit notifications come...?
> 
> Sincerely,
> 
> Bill Messmer
> wmessmer@microsoft.com<mailto:wmessmer@microsoft.com>

Hi Bill,

I don't quite understand the situation you are describing.  Can you
maybe send a log of the communication between your tool and GDBserver?

Simon

       reply	other threads:[~2022-09-11 18:55 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <MN2PR21MB14398C0638256C6DD545FA7CC4439@MN2PR21MB1439.namprd21.prod.outlook.com>
2022-09-11 18:55 ` Simon Marchi [this message]
2022-09-12 18:42   ` [EXTERNAL] " Bill Messmer
2022-09-13 23:39     ` Simon Marchi
2022-09-30 21:08       ` Bill Messmer
2022-10-19 16:19         ` Simon Marchi

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