Re: [Qemu-devel] [PATCH v2 04/23] target-arm: preserve RAO/WI bits of ARMv7 SCTLR

[Peter Maydell]

On 14 May 2014 06:43, Sergey Fedorov <address@hidden> wrote:
>
> On 13.05.2014 20:15, Fabian Aggeler wrote:
>> From: Svetlana Fedoseeva <address@hidden>
>>
>> Signed-off-by: Svetlana Fedoseeva <address@hidden>
>> Signed-off-by: Sergey Fedorov <address@hidden>
>> Signed-off-by: Fabian Aggeler <address@hidden>
>> ---
>>  target-arm/helper.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/target-arm/helper.c b/target-arm/helper.c
>> index 9c3269f..2b57ad9 100644
>> --- a/target-arm/helper.c
>> +++ b/target-arm/helper.c
>> @@ -2083,6 +2083,11 @@ static void sctlr_write(CPUARMState *env, const 
>> ARMCPRegInfo *ri,
>>  {
>>      ARMCPU *cpu = arm_env_get_cpu(env);
>>
>> +    if (arm_feature(env, ARM_FEATURE_V7)) {
>> +        value |= SCTLR_XP | SCTLR_U | SCTLR_nTWE | SCTLR_nTWI | SCTLR_L
>> +                | SCTLR_CP15BEN | SCTLR_P; /* These bits are RAO/WI */
>
> Actually, some of these bits are RAO/WI since v6. Also, there are some
> RAZ/WI bits varying over architecture variants. There is some overview
> at ARM ARM v7-AP section L.7.4. Maybe it is worth to fix more precisely
> over supported architecture variants? By the way, this patch could be
> separated from security extensions support patch set.

Agreed. Our compliance for bits that should-be-0/1 is not great,
but if we don't actually need to do those fixes for TZ support
then they're probably better separated out (ie drop them from
this patchset for the moment and submit them separately or
later...)

Also for v8 many of these RAZ/RAO bits become RES0/RES1 and
the rules are different...

thanks
-- PMM