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Thu, 12 Oct 2023 06:02:54 -0700 (PDT) Received: from localhost ([31.111.84.209]) by smtp.gmail.com with ESMTPSA id j24-20020a170906051800b00993470682e5sm11007167eja.32.2023.10.12.06.02.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Oct 2023 06:02:54 -0700 (PDT) To: Luis Machado Cc: gdb@sourceware.org Subject: Re: Thread Specific Architectures And Python Unwinder API In-Reply-To: <29fefb89-9934-4e9d-9ea0-adf40789e921@arm.com> References: <87bkd5czqr.fsf@redhat.com> <05568109-8df9-4a48-af04-9f784bf0e4d8@arm.com> <29fefb89-9934-4e9d-9ea0-adf40789e921@arm.com> Date: Thu, 12 Oct 2023 14:02:53 +0100 Message-ID: <87wmvsat8i.fsf@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gdb@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Andrew Burgess via Gdb Reply-To: Andrew Burgess Errors-To: gdb-bounces+public-inbox=simark.ca@sourceware.org Sender: "Gdb" Luis Machado writes: > On 10/11/23 11:06, Luis Machado wrote: >> Hi Andrew, >> >> On 10/11/23 09:47, Andrew Burgess wrote: >>> >>> Hi Luis, >>> >>> While working on something else I was looking at the Python Unwinder API >>> code, and I suspect that the thread-specific architectures support might >>> (currently) break the Python Unwinder support. >>> >>> If it is, then I think the fix is pretty simple, but before I posted it, >>> I wondered if you could confirm that things are indeed, currently >>> broken. >>> >>> Attached at the end of this email is a Python unwinder. You'll need to >>> supply your own test program that makes use of sve/sme, and thus uses >>> thread-specific architectures. >>> >>> What you'll need to do is: >>> >>> $ gdb -q test_file_that_uses_sve_sme >>> Reading symbols from .... etc ... >>> (gdb) source ./unwinder.py >>> (gdb) break function_where_a_thread_specific_arch_will_be_in_use >>> Breakpoint 1 at ... etc ... >>> (gdb) run >>> Starting program: ... etc ... >>> >>> Now at this point, when you stop, you should see at least one instance >>> of the banner: >>> >>> *********************************** >>> * Have executed the test unwinder * >>> *********************************** >>> >>> being printed, probably more. As you step though the function you >>> should see more instances of the banner being printed. >>> >>> To reveal the bug then it is important that when GDB stops in >>> function_where_a_thread_specific_arch_will_be_in_use, the per-thread >>> gdbarch that it creates _must_ be different from the inferior wide, >>> top-level gdbarch. >>> >>> If you don't see the banner then my suspicion is correct, and the Python >>> Unwinder API was broken when the thread-specific architecture support >>> was added. > > I've confirmed I don't see the banner. So this seems to be broken. > > Is the fix to set the python unwinder hook elsewhere? Or maybe save that > information when we're trying to pick a different gdbarch? I'll post my patch for this later today. But I'm going to propose changing the 'architecture_changed' observable into a 'new_architecture' observable (which is called in a different place). As such, every new architecture will have the Python unwinder registered correctly. I just need to update the commit message with some details of this issue as justification for the change, and I'll post it -- it's a pretty small change. I'll CC you on the new thread. Thanks, Andrew