diff options
Diffstat (limited to 'target/arm/cpu.c')
| -rw-r--r-- | target/arm/cpu.c | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/target/arm/cpu.c b/target/arm/cpu.c index 9f2ca6633a..fdc3eda318 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -1959,13 +1959,22 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp) if (!cpu->gt_cntfrq_hz) { /* - * 0 means "the board didn't set a value, use the default". - * The default value of the generic timer frequency (as seen in - * CNTFRQ_EL0) is 62.5MHz, which corresponds to a period of 16ns. - * This is what you get (a) for a CONFIG_USER_ONLY CPU (b) if the - * board doesn't set it. + * 0 means "the board didn't set a value, use the default". (We also + * get here for the CONFIG_USER_ONLY case.) + * ARMv8.6 and later CPUs architecturally must use a 1GHz timer; before + * that it was an IMPDEF choice, and QEMU initially picked 62.5MHz, + * which gives a 16ns tick period. + * + * We will use the back-compat value: + * - for QEMU CPU types added before we standardized on 1GHz + * - for versioned machine types with a version of 9.0 or earlier */ - cpu->gt_cntfrq_hz = GTIMER_DEFAULT_HZ; + if (arm_feature(env, ARM_FEATURE_BACKCOMPAT_CNTFRQ) || + cpu->backcompat_cntfrq) { + cpu->gt_cntfrq_hz = GTIMER_BACKCOMPAT_HZ; + } else { + cpu->gt_cntfrq_hz = GTIMER_DEFAULT_HZ; + } } #ifndef CONFIG_USER_ONLY @@ -2574,6 +2583,8 @@ static Property arm_cpu_properties[] = { mp_affinity, ARM64_AFFINITY_INVALID), DEFINE_PROP_INT32("node-id", ARMCPU, node_id, CPU_UNSET_NUMA_NODE_ID), DEFINE_PROP_INT32("core-count", ARMCPU, core_count, -1), + /* True to default to the backward-compat old CNTFRQ rather than 1Ghz */ + DEFINE_PROP_BOOL("backcompat-cntfrq", ARMCPU, backcompat_cntfrq, false), DEFINE_PROP_END_OF_LIST() }; |