Re: [PATCH v3 30/33] target/arm/ptw: remove TARGET_AARCH64 from arm_casq_ptw

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 5/1/25 9:24 AM, Richard Henderson wrote:
> On 4/30/25 23:23, Pierrick Bouvier wrote:
>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>> ---
>>    target/arm/ptw.c | 13 ++++++++-----
>>    1 file changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/target/arm/ptw.c b/target/arm/ptw.c
>> index 424d1b54275..f428c9b9267 100644
>> --- a/target/arm/ptw.c
>> +++ b/target/arm/ptw.c
>> @@ -737,7 +737,14 @@ static uint64_t arm_casq_ptw(CPUARMState *env, uint64_t old_val,
>>                                 uint64_t new_val, S1Translate *ptw,
>>                                 ARMMMUFaultInfo *fi)
>>    {
>> -#if defined(TARGET_AARCH64) && defined(CONFIG_TCG)
>> +#ifndef CONFIG_TCG
>> +    /* non-TCG guests only use debug-mode. */
>> +    g_assert_not_reached();
>> +#endif
>> +
>> +    /* AArch32 does not have FEAT_HADFS */
>> +    g_assert(arm_feature(env, ARM_FEATURE_AARCH64));
>> +
> 
> I don't think we need an assert here.
> 
> The ifdef for aarch64 also protects the qatomic_cmpxchg__nocheck below, because aarch64
> guest can only be built with a 64-bit host.
> 
> Are we still able to build qemu-system-arm on a 32-bit host with these changes?  It may be
> tricky to check, because the two easiest 32-bit hosts (i686, armv7) also happen to have a
> 64-bit cmpxchg.  I think "make docker-test-build@debian-mipsel-cross" will be the right test.
>

Good catch.
I was indeed building only with i686. I'll add mipsel instead.

/usr/lib/gcc-cross/mipsel-linux-gnu/12/../../../../mipsel-linux-gnu/bin/ld:
libtarget_system_arm.a.p/target_arm_ptw.c.o: undefined reference to
symbol '__atomic_compare_exchange_8@@LIBATOMIC_1.0'

> If that fails, I think you could s/TARGET_AARCH64/CONFIG_ATOMIC64/ here.
> 

I'll revert this change and simply do this replace, adding a comment as 
well.

> 
> r~