@@ -6567,11 +6567,21 @@ static void define_debug_regs(ARMCPU *cpu)
*/
int i;
int wrps, brps, ctx_cmps;
- ARMCPRegInfo dbgdidr = {
- .name = "DBGDIDR", .cp = 14, .crn = 0, .crm = 0, .opc1 = 0, .opc2 = 0,
- .access = PL0_R, .accessfn = access_tda,
- .type = ARM_CP_CONST, .resetvalue = cpu->isar.dbgdidr,
- };
+
+ /*
+ * The Arm ARM says DBGDIDR is optional and deprecated if EL1 cannot
+ * use AArch32. Given that bit 15 is RES1, if the value is 0 then
+ * the register must not exist for this cpu.
+ */
+ if (cpu->isar.dbgdidr != 0) {
+ ARMCPRegInfo dbgdidr = {
+ .name = "DBGDIDR", .cp = 14, .crn = 0, .crm = 0,
+ .opc1 = 0, .opc2 = 0,
+ .access = PL0_R, .accessfn = access_tda,
+ .type = ARM_CP_CONST, .resetvalue = cpu->isar.dbgdidr,
+ };
+ define_one_arm_cp_reg(cpu, &dbgdidr);
+ }
/* Note that all these register fields hold "number of Xs minus 1". */
brps = arm_num_brps(cpu);
@@ -6580,7 +6590,6 @@ static void define_debug_regs(ARMCPU *cpu)
assert(ctx_cmps <= brps);
- define_one_arm_cp_reg(cpu, &dbgdidr);
define_arm_cp_regs(cpu, debug_cp_reginfo);
if (arm_feature(&cpu->env, ARM_FEATURE_LPAE)) {
Only define the register if it exists for the cpu. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- I've pulled this out of a largely defunct 2019 branch. This will be required for the cortex-a76, which only implements aa32 at el0. This did get some review, back in the day, https://lists.gnu.org/archive/html/qemu-devel/2019-04/msg05171.html but it has changed enough that I didn't include the proffered r-b. r~ --- target/arm/helper.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)