Re: [Qemu-devel] [PATCH] nvic: Change NVIC to support ARMv6-M

[Peter Maydell]

On 11 July 2018 at 14:25, Stefan Hajnoczi <address@hidden> wrote:
> On Tue, Jul 10, 2018 at 06:33:35PM +0300, Julia Suvorova via Qemu-devel wrote:
>> The differences from ARMv7-M NVIC are:
>>   * ARMv6-M only supports up to 32 external interrupts
>>    (configurable feature already). The ICTR is reserved.
>>   * Active Bit Register is reserved.
>>   * ARMv6-M supports 4 priority levels against 256 in ARMv7-M.
>>
>> Signed-off-by: Julia Suvorova <address@hidden>
>> ---
>>  hw/intc/armv7m_nvic.c | 29 +++++++++++++++++++++++++----
>>  1 file changed, 25 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/intc/armv7m_nvic.c b/hw/intc/armv7m_nvic.c
>> index 38aaf3dc8e..8545c87caa 100644
>> --- a/hw/intc/armv7m_nvic.c
>> +++ b/hw/intc/armv7m_nvic.c
>> @@ -420,6 +420,10 @@ static void set_prio(NVICState *s, unsigned irq, bool 
>> secure, uint8_t prio)
>>      assert(irq > ARMV7M_EXCP_NMI); /* only use for configurable prios */
>>      assert(irq < s->num_irq);
>>
>> +    if (!arm_feature(&s->cpu->env, ARM_FEATURE_V7)) {
>
> ARMv8-M also has the NVIC:
> https://static.docs.arm.com/ddi0553/a/DDI0553A_e_armv8m_arm.pdf
>
> Should arm_feature(&s->cpu->env, ARM_FEATURE_V6) be used instead of
> !arm_feature(&s->cpu->env, ARM_FEATURE_V7)?

All of v6M, v7M and v8M cores will set ARM_FEATURE_V6, so
testing on it doesn't distinguish them.

thanks
-- PMM