[mepc] use CPU BOOT_ADDR as reset value

stnolting · Nov 1, 2024 · b3155be · b3155be
1 parent cbfd473
commit b3155be
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diff --git a/docs/datasheet/cpu_csr.adoc b/docs/datasheet/cpu_csr.adoc
@@ -360,7 +360,7 @@ As software does not need to determine the interrupt cause the reduction in late
 |=======================
 | Name        | Machine exception program counter
 | Address     | `0x341`
-| Reset value | `0x00000000`
+| Reset value | `BOOT_ADDR` (CPU boot address, see <<_cpu_top_entity_generics>>)
 | ISA         | `Zicsr`
 | Description | The `mepc` CSR provides the instruction address where execution has stopped/failed when
 an interrupt is triggered / an exception is raised. See section <<_traps_exceptions_and_interrupts>> for a list of all legal values.

diff --git a/rtl/core/neorv32_cpu_control.vhd b/rtl/core/neorv32_cpu_control.vhd
@@ -1410,7 +1410,7 @@ begin
       csr.mie_firq       <= (others => '0');
       csr.mtvec          <= (others => '0');
       csr.mscratch       <= x"19880704";
-      csr.mepc           <= (others => '0');
+      csr.mepc           <= BOOT_ADDR(XLEN-1 downto 2) & "00"; -- 32-bit-aligned boot address
       csr.mcause         <= (others => '0');
       csr.mtval          <= (others => '0');
       csr.mtinst         <= (others => '0');