Matteo Concas commented on a discussion: https://gitlab.rtems.org/rtems/rtos/rtems/-/issues/5383#note_135544 > After looking at grmon4 a bit, it occurs to me that grmon does not support > emulation Indeed GRMON is only used to connect to hardware, we also have TSIM for simulation but we don't provide a trial version of the NOEL-V one. >From more testing, I have noticed that this misaligned load is executed twice. >The first time during system initialization when the DTB is parsed to find the >end of the memory area in `bsp_memory_initialize()`. The CPU then goes to the >exception handler as expected and `_Terminate()` is called. But, on system >termination information is printed out to the console, to do that `printk()` >which in turn will call `riscv_output_char_init()` and this function probe the >FDT to find the console. During this parsing the same error is encountered but >this time the exception handler is never entered. I suspect that is because of the [double trap extension (Smdbltrp)](https://docs.riscv.org/reference/isa/priv/smdbltrp.html) when combined with the [Resumable Non-Maskable Interrupts extension (Smrnmi)](https://docs.riscv.org/reference/isa/priv/rnmi.html#rnmi). In this case, if a double trap happens the RNMI handler should be called but RTEMS doesn't set this anywhere as far as I know meaning `pc` is set to whatever the reset value of the RNMI is (which is implementation defined). I need to check the CSR address in NOEL-V (also implementation defined) and then decide what we want to do in that case? Calling the exception handler a third time won't work obviously.. Showing the double exception along with a register dump: ``` grmon4> bp _RISCV_Exception_handler Software breakpoint 1 at <_RISCV_Exception_handler> grmon4> run CPU 0: Breakpoint 1 hit 0x0000000000005c7c: eb010113 addi sp, sp, -336 <$xrv64i2p1_m2p0_a2p1_f2p2_d2p2_zicsr2p0_zmmul1p0_zaamo1p0_zalrsc1p0+0> CPU 1: Forced into debug mode 0x00000000000000ac: ffdff06f j 0xa8 grmon4> inst 10 TIME L P ADDRESS INSTRUCTION RESULT SYMBOL 95902 1 M 000000000000e5e4 beqz a0, 0xe5f0 [0000000000000000] fdt_get_property_namelen_+0xe8 95907 0 M 000000000000e5e8 lw a5, 12(sp) [000000000000000e] fdt_get_property_namelen_+0xec 95907 1 M 000000000000e5ec beq a5, s3, 0xe65c [000000000000000e] fdt_get_property_namelen_+0xf0 95982 0 M 000000000000e65c mv a2, s3 [000000000000000e] fdt_get_property_namelen_+0x160 95983 0 M 000000000000e660 mv a1, s6 [0000000000018a70] fdt_get_property_namelen_+0x164 95983 1 M 000000000000e664 jal ra, 0x13e38 [000000000000e668] fdt_get_property_namelen_+0x168 95985 0 M 0000000000013e38 li a3, 7 [0000000000000007] memcmp+0x0 95985 1 M 0000000000013e3c bgeu a3, a2, 0x13e5c [0000000000000007] memcmp+0x4 95986 0 M 0000000000013e40 ld a4, 0(a0) [MISALIGNED LOAD 000000000001b5f9] memcmp+0x8 96057 0 M 0000000000005c7c addi sp, sp, -336 [ BREAKPOINT ] $xrv64i2p1_m2p0_a2p1_f2p2_d2p2_zicsr2p0_zmmul1p0_zaamo1p0_zalrsc1p0+0x0 grmon4> cont CPU 0: Error mode (4, Load address misaligned) 0x0000000030011000: 0000 illegal instruction CPU 1: Forced into debug mode 0x00000000000000ac: ffdff06f j 0xa8 grmon4> inst 10 TIME L P ADDRESS INSTRUCTION RESULT SYMBOL 103960 1 M 000000000000e428 ret [000000000000e42c] fdt_get_string+0x120 103962 1 M 000000000000e5e4 beqz a0, 0xe5f0 [0000000000000000] fdt_get_property_namelen_+0xe8 103967 0 M 000000000000e5e8 lw a5, 12(sp) [000000000000000a] fdt_get_property_namelen_+0xec 103967 1 M 000000000000e5ec beq a5, s3, 0xe65c [000000000000000a] fdt_get_property_namelen_+0xf0 103974 0 M 000000000000e65c mv a2, s3 [000000000000000a] fdt_get_property_namelen_+0x160 103975 0 M 000000000000e660 mv a1, s6 [0000000000018858] fdt_get_property_namelen_+0x164 103975 1 M 000000000000e664 jal ra, 0x13e38 [000000000000e668] fdt_get_property_namelen_+0x168 103977 0 M 0000000000013e38 li a3, 7 [0000000000000007] memcmp+0x0 103977 1 M 0000000000013e3c bgeu a3, a2, 0x13e5c [0000000000000007] memcmp+0x4 103978 0 M 0000000000013e40 ld a4, 0(a0) [MISALIGNED LOAD 000000000001b5dc] memcmp+0x8 grmon4> reg a0: 000000000001b5dc t0: 00000000000000e0 s0: 0000000000000050 a1: 0000000000018858 t1: 0000000000000000 s1: 000000000001a3d8 a2: 000000000000000a t2: 0000000000014648 s2: 00000000000601c8 a3: 0000000000000007 t3: 0000000000000001 s3: 000000000000000a a4: 000000000001b5e0 t4: 0000000000000000 s4: 0000000000000003 a5: 000000000000000a t5: 0000000000000000 s5: 0000000000000009 a6: 0000000000000000 t6: 0000000000000000 s6: 0000000000018858 a7: ffffffffffffffff s7: 0000000000000004 s8: 00000000000601ac Machine mode sp: 0000000000060130 s9: 000000000001a460 FPU dirty state tp: 0000000000000000 s10: 0000000000000000 IRQ disabled gp: 000000000005bc48 s11: 0000000000000000 ra: 000000000000e668 <fdt_get_property_namelen_+0x16c> pc: 0000000030011000 illegal instruction grmon4> reg mtvec mepc mtval mcause mstatus mtvec = 23676 (0x0000000000005c7c) mepc = 81472 (0x0000000000013e40) mtval = 112121 (0x000000000001b5f9) mcause = 4 (0x0000000000000004) mstatus = 9223376477850990592 (0x8000040a00007800) ``` -- View it on GitLab: https://gitlab.rtems.org/rtems/rtos/rtems/-/issues/5383#note_135544 You're receiving this email because of your account on gitlab.rtems.org.
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