Gdbserver registers response shorter than gdb expects

[ccrause]

Testing Bloom with gdb 10.2 resulted in gdb complaining the response to the 'g' request is truncated. Inspection shows that the response is one byte shorter than the expected length of 32+1+2+4 = 39 bytes (or 78 hex digits). Please find the gdb session below.

$ ~/gdb/avr-gcc-11.1.0-x64-linux/bin/avr-gdb GNU gdb (GDB) 10.2 Copyright (C) 2021 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "--host=x86_64-pc-linux-gnu --target=avr". Type "show configuration" for configuration details. For bug reporting instructions, please see: https://www.gnu.org/software/gdb/bugs/. Find the GDB manual and other documentation resources online at: http://www.gnu.org/software/gdb/documentation/.

For help, type "help". Type "apropos word" to search for commands related to "word". (gdb) set debug remote 1 (gdb) fil testbreak.X.debug.elf Reading symbols from testbreak.X.debug.elf... (gdb) tar rem :1234 Remote debugging using :1234 Sending packet: $qSupported:multiprocess+;swbreak+;hwbreak+;qRelocInsn+;fork-events+;vfork-events+;exec-events+;vContSupported+;QThreadEvents+;no-resumed+#df...Ack Packet received: qSupported:swbreak+;PacketSize=1024; Packet qSupported (supported-packets) is supported Sending packet: $vMustReplyEmpty#3a...Ack Packet received: \000 Sending packet: $Hg0#df...Ack Packet received: \000 Sending packet: $qTStatus#49...Ack Packet received: \000 Packet qTStatus (trace-status) is NOT supported Sending packet: $?#3f...Ack Packet received: T05 Sending packet: $qfThreadInfo#bb...Ack Packet received: \000 Sending packet: $qL1200000000000000000#50...Ack Packet received: \000 Sending packet: $Hc-1#09...Ack Packet received: \000 Sending packet: $qC#b4...Ack Packet received: \000 Sending packet: $qAttached#8f...Ack Packet received: \001 Packet qAttached (query-attached) is supported Sending packet: $qOffsets#4b...Ack Packet received: \000 Sending packet: $g#67...Ack Packet received: ff00ffffbffffffd7fdffffdbeffbfffffffffffffbfefff20000301df08370000df00000000 Truncated register 34 in remote 'g' packet (gdb) info registers The program has no registers now.

[navnavnav]

Can you attach the debug log please?

[ccrause]

Certainly, Bloom log:

$ bloom 2021-12-23 22:50:23 SAST [MT] [1]: [DEBUG] Debug log printing has been enabled. 2021-12-23 22:50:23 SAST [MT] [2]: [INFO] Selected environment: default 2021-12-23 22:50:23 SAST [MT] [3]: [DEBUG] Number of environments extracted from config: 1 2021-12-23 22:50:23 SAST [SH] [4]: [DEBUG] Starting SignalHandler 2021-12-23 22:50:23 SAST [SH] [5]: [DEBUG] SignalHandler ready 2021-12-23 22:50:23 SAST [TC] [6]: [INFO] Starting TargetController 2021-12-23 22:50:23 SAST [TC] [7]: [INFO] Connecting to debug tool 2021-12-23 22:50:23 SAST [TC] [8]: [DEBUG] HID device path: 0001:0022:00 2021-12-23 22:50:23 SAST [TC] [9]: [INFO] Debug tool connected 2021-12-23 22:50:23 SAST [TC] [10]: [INFO] Debug tool name: MPLAB Snap 2021-12-23 22:50:23 SAST [TC] [11]: [INFO] Debug tool serial: 2021-12-23 22:50:23 SAST [TC] [12]: [DEBUG] Loading AVR8 target description file: /opt/bloom/bin/../resources/TargetDescriptionFiles/AVR/AVR8/TINY/ATTINY24A.xml 2021-12-23 22:50:23 SAST [TC] [13]: [DEBUG] Failed to extract pinout from target description element - Failed to convert position attribute value to integer on pin element 0 2021-12-23 22:50:23 SAST [TC] [14]: [WARNING] AVR8 debugWire interface selected - the DWEN fuse will need to be enabled 2021-12-23 22:50:23 SAST [TC] [15]: [INFO] Activating target 2021-12-23 22:50:23 SAST [TC] [16]: [DEBUG] Setting DEVICE_FLASH_PAGE_SIZE AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [17]: [DEBUG] Setting DEVICE_FLASH_SIZE AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [18]: [DEBUG] Setting DEVICE_FLASH_BASE AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [19]: [DEBUG] Setting DEVICE_SRAM_START AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [20]: [DEBUG] Setting DEVICE_EEPROM_SIZE AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [21]: [DEBUG] Setting DEVICE_EEPROM_PAGE_SIZE AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [22]: [DEBUG] Setting DEVICE_OCD_REVISION AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [23]: [DEBUG] Setting DEVICE_OCD_DATA_REGISTER AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [24]: [DEBUG] Setting DEVICE_SPMCR_REGISTER AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [25]: [DEBUG] Setting DEVICE_OSCCAL_ADDR AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [26]: [DEBUG] Setting DEVICE_EEARL_ADDR AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [27]: [DEBUG] Setting DEVICE_EEARH_ADDR AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [28]: [DEBUG] Setting DEVICE_EECR_ADDR AVR8 parameter 2021-12-23 22:50:23 SAST [TC] [29]: [DEBUG] Setting DEVICE_EEDR_ADDR AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [30]: [INFO] Target activated 2021-12-23 22:50:24 SAST [TC] [31]: [INFO] AVR8 target promoted to tinyAVR target 2021-12-23 22:50:24 SAST [TC] [32]: [DEBUG] Setting DEVICE_FLASH_PAGE_SIZE AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [33]: [DEBUG] Setting DEVICE_FLASH_SIZE AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [34]: [DEBUG] Setting DEVICE_FLASH_BASE AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [35]: [DEBUG] Setting DEVICE_SRAM_START AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [36]: [DEBUG] Setting DEVICE_EEPROM_SIZE AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [37]: [DEBUG] Setting DEVICE_EEPROM_PAGE_SIZE AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [38]: [DEBUG] Setting DEVICE_OCD_REVISION AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [39]: [DEBUG] Setting DEVICE_OCD_DATA_REGISTER AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [40]: [DEBUG] Setting DEVICE_SPMCR_REGISTER AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [41]: [DEBUG] Setting DEVICE_OSCCAL_ADDR AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [42]: [DEBUG] Setting DEVICE_EEARL_ADDR AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [43]: [DEBUG] Setting DEVICE_EEARH_ADDR AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [44]: [DEBUG] Setting DEVICE_EECR_ADDR AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [45]: [DEBUG] Setting DEVICE_EEDR_ADDR AVR8 parameter 2021-12-23 22:50:24 SAST [TC] [46]: [INFO] Target ID: 0x1e910b 2021-12-23 22:50:24 SAST [TC] [47]: [INFO] Target name: ATtiny24A 2021-12-23 22:50:24 SAST [TC] [48]: [DEBUG] Event "TargetControllerThreadStateChanged" (2) registered for listener ApplicationEventListener 2021-12-23 22:50:24 SAST [TC] [49]: [DEBUG] TargetController ready and waiting for events. 2021-12-23 22:50:24 SAST [MT] [50]: [INFO] Selected DebugServer: AVR GDB Remote Serial Protocol Debug Server 2021-12-23 22:50:24 SAST [DS] [51]: [INFO] Starting DebugServer 2021-12-23 22:50:24 SAST [TC] [52]: [DEBUG] Target state changed - STOPPED 2021-12-23 22:50:24 SAST [DS] [53]: [DEBUG] Event "ExtractTargetDescriptor" (3) registered for listener TargetControllerEventListener 2021-12-23 22:50:24 SAST [TC] [54]: [DEBUG] Dispatching event ExtractTargetDescriptor (3). 2021-12-23 22:50:24 SAST [TC] [55]: [DEBUG] Event "TargetDescriptorExtracted" (5) registered for listener DebugServerEventListener 2021-12-23 22:50:24 SAST [DS] [56]: [INFO] GDB RSP address: 127.0.0.1 2021-12-23 22:50:24 SAST [DS] [57]: [INFO] GDB RSP port: 1234 2021-12-23 22:50:24 SAST [DS] [58]: [DEBUG] Event "DebugServerThreadStateChanged" (6) registered for listener ApplicationEventListener 2021-12-23 22:50:24 SAST [DS] [59]: [INFO] DebugServer ready 2021-12-23 22:50:24 SAST [DS] [60]: [INFO] Waiting for GDB RSP connection 2021-12-23 22:50:24 SAST [DS] [61]: [DEBUG] GDB RSP interrupted 2021-12-23 22:50:24 SAST [DS] [62]: [INFO] Waiting for GDB RSP connection 2021-12-23 22:50:25 SAST [MT] [63]: [INFO] Starting Insight 2021-12-23 22:50:25 SAST [MT] [64]: [DEBUG] Event "ExtractTargetDescriptor" (7) registered for listener TargetControllerEventListener 2021-12-23 22:50:25 SAST [TC] [65]: [DEBUG] Dispatching event ExtractTargetDescriptor (7). 2021-12-23 22:50:25 SAST [TC] [66]: [DEBUG] Event "TargetDescriptorExtracted" (8) registered for listener InsightEventListener 2021-12-23 22:50:25 SAST [MT] [67]: [DEBUG] Number of target variants supported by Insight: 3 2021-12-23 22:50:25 SAST [MT] [68]: [INFO] Insight ready 2021-12-23 22:50:25 SAST [IW] [69]: [DEBUG] Starting InsightWorker thread 2021-12-23 22:50:25 SAST [IW] [70]: [DEBUG] Event "InsightThreadStateChanged" (9) registered for listener TargetControllerEventListener 2021-12-23 22:50:25 SAST [TC] [71]: [DEBUG] Dispatching event InsightThreadStateChanged (9). 2021-12-23 22:50:25 SAST [TC] [72]: [DEBUG] Target state changed - STOPPED 2021-12-23 22:50:25 SAST [TC] [73]: [DEBUG] Event "TargetExecutionStopped" (10) registered for listener DebugServerEventListener 2021-12-23 22:50:25 SAST [TC] [74]: [DEBUG] Event "TargetExecutionStopped" (10) registered for listener InsightWorkerEventListener 2021-12-23 22:50:25 SAST [DS] [75]: [DEBUG] GDB RSP interrupted 2021-12-23 22:50:25 SAST [DS] [76]: [DEBUG] Dispatching event TargetExecutionStopped (10). 2021-12-23 22:50:25 SAST [DS] [77]: [INFO] Waiting for GDB RSP connection 2021-12-23 22:50:25 SAST [IW] [78]: [DEBUG] Dispatching event TargetExecutionStopped (10). 2021-12-23 22:50:26 SAST [IW] [79]: [DEBUG] Event "RetrieveTargetPinStates" (11) registered for listener TargetControllerEventListener 2021-12-23 22:50:26 SAST [TC] [80]: [DEBUG] Dispatching event RetrieveTargetPinStates (11). 2021-12-23 22:50:26 SAST [TC] [81]: [DEBUG] Event "TargetPinStatesRetrieved" (12) registered for listener InsightWorkerEventListener 2021-12-23 22:50:44 SAST [DS] [82]: [INFO] Accepted GDP RSP connection from 127.0.0.1 2021-12-23 22:50:44 SAST [DS] [83]: [DEBUG] Event "DebugSessionStarted" (13) registered for listener TargetControllerEventListener 2021-12-23 22:50:44 SAST [TC] [84]: [DEBUG] Dispatching event DebugSessionStarted (13). 2021-12-23 22:50:44 SAST [DS] [85]: [DEBUG] Event "ReportTargetControllerState" (14) registered for listener TargetControllerEventListener 2021-12-23 22:50:44 SAST [TC] [86]: [DEBUG] Dispatching event ReportTargetControllerState (14). 2021-12-23 22:50:44 SAST [TC] [87]: [DEBUG] Event "TargetControllerStateReported" (15) registered for listener DebugServerEventListener 2021-12-23 22:50:44 SAST [TC] [88]: [DEBUG] Event "TargetControllerStateReported" (15) registered for listener InsightWorkerEventListener 2021-12-23 22:50:44 SAST [DS] [89]: [DEBUG] GDB client data received (142 bytes): +$qSupported:multiprocess+;swbreak+;hwbreak+;qRelocInsn+;fork-events+;vfork-events+;exec-events+;vContSupported+;QThreadEvents+;no-resumed+#df 2021-12-23 22:50:44 SAST [DS] [90]: [DEBUG] Writing packet: + 2021-12-23 22:50:44 SAST [IW] [91]: [DEBUG] Dispatching event TargetControllerStateReported (15). 2021-12-23 22:50:44 SAST [DS] [92]: [DEBUG] Handling QuerySupport packet 2021-12-23 22:50:44 SAST [DS] [93]: [DEBUG] Writing packet: $qSupported:swbreak+;PacketSize=1024;#f8 2021-12-23 22:50:44 SAST [DS] [94]: [DEBUG] GDB client data received (19 bytes): $vMustReplyEmpty#3a 2021-12-23 22:50:44 SAST [DS] [95]: [DEBUG] Writing packet: + 2021-12-23 22:50:44 SAST [DS] [96]: [DEBUG] Unknown GDB RSP packet: vMustReplyEmpty - returning empty response 2021-12-23 22:50:44 SAST [DS] [97]: [DEBUG] Writing packet: $#00 2021-12-23 22:50:44 SAST [DS] [98]: [DEBUG] GDB client data received (7 bytes): $Hg0#df 2021-12-23 22:50:44 SAST [DS] [99]: [DEBUG] Writing packet: + 2021-12-23 22:50:44 SAST [DS] [100]: [DEBUG] Unknown GDB RSP packet: Hg0 - returning empty response 2021-12-23 22:50:44 SAST [DS] [101]: [DEBUG] Writing packet: $#00 2021-12-23 22:50:44 SAST [DS] [102]: [DEBUG] GDB client data received (12 bytes): $qTStatus#49 2021-12-23 22:50:44 SAST [DS] [103]: [DEBUG] Writing packet: + 2021-12-23 22:50:44 SAST [DS] [104]: [DEBUG] Unknown GDB RSP packet: qTStatus - returning empty response 2021-12-23 22:50:44 SAST [DS] [105]: [DEBUG] Writing packet: $#00 2021-12-23 22:50:44 SAST [DS] [106]: [DEBUG] GDB client data received (5 bytes): $?#3f 2021-12-23 22:50:44 SAST [DS] [107]: [DEBUG] Writing packet: + 2021-12-23 22:50:44 SAST [DS] [108]: [DEBUG] Writing packet: $T05#b9 2021-12-23 22:50:44 SAST [DS] [109]: [DEBUG] GDB client data received (16 bytes): $qfThreadInfo#bb 2021-12-23 22:50:44 SAST [DS] [110]: [DEBUG] Writing packet: + 2021-12-23 22:50:44 SAST [DS] [111]: [DEBUG] Unknown GDB RSP packet: qfThreadInfo - returning empty response 2021-12-23 22:50:44 SAST [DS] [112]: [DEBUG] Writing packet: $#00 2021-12-23 22:50:44 SAST [DS] [113]: [DEBUG] GDB client data received (25 bytes): $qL1200000000000000000#50 2021-12-23 22:50:44 SAST [DS] [114]: [DEBUG] Writing packet: + 2021-12-23 22:50:44 SAST [DS] [115]: [DEBUG] Unknown GDB RSP packet: qL1200000000000000000 - returning empty response 2021-12-23 22:50:44 SAST [DS] [116]: [DEBUG] Writing packet: $#00 2021-12-23 22:50:44 SAST [DS] [117]: [DEBUG] GDB client data received (8 bytes): $Hc-1#09 2021-12-23 22:50:44 SAST [DS] [118]: [DEBUG] Writing packet: + 2021-12-23 22:50:44 SAST [DS] [119]: [DEBUG] Unknown GDB RSP packet: Hc-1 - returning empty response 2021-12-23 22:50:44 SAST [DS] [120]: [DEBUG] Writing packet: $#00 2021-12-23 22:50:45 SAST [DS] [121]: [DEBUG] GDB client data received (6 bytes): $qC#b4 2021-12-23 22:50:45 SAST [DS] [122]: [DEBUG] Writing packet: + 2021-12-23 22:50:45 SAST [DS] [123]: [DEBUG] Unknown GDB RSP packet: qC - returning empty response 2021-12-23 22:50:45 SAST [DS] [124]: [DEBUG] Writing packet: $#00 2021-12-23 22:50:45 SAST [DS] [125]: [DEBUG] GDB client data received (13 bytes): $qAttached#8f 2021-12-23 22:50:45 SAST [DS] [126]: [DEBUG] Writing packet: + 2021-12-23 22:50:45 SAST [DS] [127]: [DEBUG] Handling qAttached 2021-12-23 22:50:45 SAST [DS] [128]: [DEBUG] Writing packet: $#01 2021-12-23 22:50:45 SAST [DS] [129]: [DEBUG] GDB client data received (5 bytes): $g#67 2021-12-23 22:50:45 SAST [DS] [130]: [DEBUG] Writing packet: + 2021-12-23 22:50:45 SAST [DS] [131]: [DEBUG] Handling ReadRegisters packet 2021-12-23 22:50:45 SAST [DS] [132]: [DEBUG] Event "RetrieveRegistersFromTarget" (16) registered for listener TargetControllerEventListener 2021-12-23 22:50:45 SAST [TC] [133]: [DEBUG] Dispatching event RetrieveRegistersFromTarget (16). 2021-12-23 22:50:45 SAST [TC] [134]: [DEBUG] Event "RegistersRetrievedFromTarget" (17) registered for listener DebugServerEventListener 2021-12-23 22:50:45 SAST [DS] [135]: [DEBUG] Writing packet: $ff00ffffbffffffd7fdffffdbeffbfffffffffffffbfefff20000301df0c370000df00000000#c4 2021-12-23 22:50:45 SAST [DS] [136]: [INFO] GDB RSP client disconnected 2021-12-23 22:50:45 SAST [DS] [137]: [DEBUG] Event "DebugSessionFinished" (18) registered for listener TargetControllerEventListener 2021-12-23 22:50:45 SAST [DS] [138]: [INFO] Waiting for GDB RSP connection 2021-12-23 22:50:45 SAST [DS] [139]: [DEBUG] GDB RSP interrupted 2021-12-23 22:50:45 SAST [DS] [140]: [INFO] Waiting for GDB RSP connection 2021-12-23 22:50:45 SAST [TC] [141]: [DEBUG] Dispatching event DebugSessionFinished (18). 2021-12-23 22:50:45 SAST [TC] [142]: [DEBUG] Suspending TargetController 2021-12-23 22:50:45 SAST [TC] [143]: [INFO] Deactivating target 2021-12-23 22:50:45 SAST [TC] [144]: [INFO] Closing debug tool 2021-12-23 22:50:45 SAST [TC] [145]: [DEBUG] Event "TargetControllerStateReported" (19) registered for listener DebugServerEventListener 2021-12-23 22:50:45 SAST [TC] [146]: [DEBUG] Event "TargetControllerStateReported" (19) registered for listener InsightWorkerEventListener 2021-12-23 22:50:45 SAST [TC] [147]: [DEBUG] TargetController suspended 2021-12-23 22:50:45 SAST [DS] [148]: [DEBUG] GDB RSP interrupted 2021-12-23 22:50:45 SAST [DS] [149]: [DEBUG] Dispatching event TargetControllerStateReported (19). 2021-12-23 22:50:45 SAST [DS] [150]: [INFO] Waiting for GDB RSP connection 2021-12-23 22:50:45 SAST [IW] [151]: [DEBUG] Dispatching event TargetControllerStateReported (19).

[navnavnav]

OK, I think I see the problem here. Your target only has a single byte SP register, and Bloom is sending it as is.

I can sort a fix for this, but it will be shipped in the next release, which is due late next week. Will keep you updated via this ticket.

[ccrause]

Thank you for investigating. Will wait for the next release.

[navnavnav]

Version 0.5.0 has just been published. It contains a fix for this issue. See website (https://bloom.oscillate.io) to download the latest version. As I don't have an any targets with a single byte SP (there are only 9 of the 249 supported targets) to test with, it would be good if you could test and update this ticket after.

I will close this ticket once I've received confirmation from you.

[ccrause]

Thanks Nav. I confirm that this issue with gdb is now fixed as tested with an attiny24A over Snap.