[SOLVED] JLink Commander cannot read/write R13 or R15

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  • JLink Commander cannot read/write R13 or R15

    The target is a GD32F303ZK. I am using SEGGER J-Link Commander V7.60d.

    I can debug the chip without problem (using IAR 5.2 or IAR 9.1), and I can flash it using JFlash or JLink commander. So generally the J-Link is working fine with the GD32F303ZK.

    However I was doing some low-level checkout because one of our boards is acting strange (though everything I copy/paste here is from a a session with a fully working board). I wanted to manipulate the R15 (PC) and R13 (SP) registers to simulate a reset to a different program that is flashed on the board, but is different than the program that is specified in the GD32's flash memory locations for the the initial SP and PC (addresses 0x0800_0000 and 0x0800_0004).

    I can use the `rreg` and `wreg` jlink commander commands to read or write any general purpose register except r13 or r15. For those registers jlink command responds "Illegal register name." "Syntax: rreg <RegName>" then proceeds to list dozens of valid register names (including "R13 (SP)" and "R15 (PC)").


    I have tried using variations of the register names, such as "r13", "R13", "sp", "SP", and even "R13 (SP)" (as given in the error message) with the same result for all of them.



    Here is a copy paste (with the list of valid register names mostly deleted to make reading easier):



    Source Code

    1. J-Link>ishalted
    2. CPU is halted (PC = 0x080271E8).
    3. J-Link>regs
    4. PC = 080271E8, CycleCnt = 809DC5AE
    5. R0 = 00000000, R1 = CDCDCDCD, R2 = 80000000, R3 = 08030CDD
    6. R4 = 6802B2F0, R5 = 00000001, R6 = 6802B2F0, R7 = CCCC0007
    7. R8 = CCCC0008, R9 = CCCC0009, R10= CCCC000A, R11= CCCC000B
    8. R12= 08030CDC
    9. SP(R13)= 20003400, MSP= 200033D8, PSP= 20003400, R14(LR) = 21000000
    10. XPSR = 01000000: APSR = nzcvq, EPSR = 01000000, IPSR = 000 (NoException)
    11. CFBP = 02000000, CONTROL = 02, FAULTMASK = 00, BASEPRI = 00, PRIMASK = 00
    13. FPS0 = 2292A714, FPS1 = 1841CC2D, FPS2 = 1826B610, FPS3 = 80094E08
    14. FPS4 = 2DC4E403, FPS5 = 06436010, FPS6 = 44102763, FPS7 = 029DAC32
    15. FPS8 = D0D0E426, FPS9 = 9487C14B, FPS10= 14B14703, FPS11= 4E1DC230
    16. FPS12= 48BB8020, FPS13= A5B141A8, FPS14= 2C81E8D1, FPS15= 80F44A30
    17. FPS16= 4C004101, FPS17= AC1281A4, FPS18= 63F88A41, FPS19= C13226B0
    18. FPS20= AA9584DA, FPS21= C0A2FA23, FPS22= 88D62E08, FPS23= 418010D1
    19. FPS24= 087B948E, FPS25= 5416064D, FPS26= 15340493, FPS27= F4C580C6
    20. FPS28= 81220252, FPS29= 02801471, FPS30= 34840245, FPS31= C06E1150
    21. FPSCR= 00000000
    22. J-Link>rreg r0
    23. R0 = 0x00000000
    24. J-Link>rreg r14
    25. R14 = 0x21000000
    26. J-Link>rreg r13
    27. Illegal register name.
    28. Syntax: rreg <RegName>
    30. R0
    31. R1
    32. R2
    33. R3
    34. R4
    35. R5
    36. R6
    37. R7
    38. R8
    39. R9
    40. R10
    41. R11
    42. R12
    43. R13 (SP)
    44. R14
    45. R15 (PC)
    46. XPSR
    48. // ... a bunch of register names edited out
    50. MSPLIM
    51. PSPLIM
    52. J-Link>rreg r15
    53. Illegal register name.
    54. Syntax: rreg <RegName>
    56. R0
    57. R1
    58. R2
    59. R3
    60. R4
    61. R5
    62. R6
    63. R7
    64. R8
    65. R9
    66. R10
    67. R11
    68. R12
    69. R13 (SP)
    70. R14
    71. R15 (PC)
    72. XPSR
    74. // ... a bunch of register names edited out
    76. MSPLIM
    77. PSPLIM
    78. J-Link>
    Display All

  • [SOLVED] JLink Commander cannot read/write R13 or R15

    Update: While the following doesn't work:

    Source Code

    1. J-Link>rreg R13 (SP)
    2. Illegal register name.
    3. Syntax: rreg <RegName>
    5. ... long list of registers elided ...


    I found that using quotes makes it work:

    Source Code

    1. J-Link>rreg "R13 (SP)"
    2. R13 (SP) = 0x20003400
    3. J-Link>rreg "R15 (PC)"
    4. R15 (PC) = 0x080271E8

    I'd like to ask for an enhancement to jlink.exe so that the simpler, more commonly used names "R13", "SP", "R15", and "PC" be accepted as aliases for the respective registers.

    I find it surprising that no one has complained about this before.

  • Hello,

    Thank you for your inquriy.
    The issue is reproducible and will be fixed.

    Best regards,
    Nino
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