Re: [Qemu-devel] [PATCH] target-arm: add support for v8 SHA1 and SHA256 instructions

[Peter Maydell]

On 25 March 2014 16:46, Andreas Färber <address@hidden> wrote:
> Am 25.03.2014 17:27, schrieb Ard Biesheuvel:
>> @@ -630,6 +630,8 @@ enum arm_features {
>>      ARM_FEATURE_V8_AES, /* implements AES part of v8 Crypto Extensions */
>>      ARM_FEATURE_CBAR, /* has cp15 CBAR */
>>      ARM_FEATURE_CRC, /* ARMv8 CRC instructions */
>> +    ARM_FEATURE_V8_SHA1, /* implements SHA1 part of v8 Crypto Extensions */
>> +    ARM_FEATURE_V8_SHA256, /* implements SHA256 part of v8 Crypto 
>> Extensions */
>>  };
>
> Do these really need to be separate features? We only have 32 feature
> bits.

No, we have 64. We overflowed 32 bits a little while back :-)

> Maybe even an ARM_FEATURE_CRYPTO for AES, SHA1, SHA256 would do?

It's arguable. The ARM ARM defines the crypto extensions as a
single extension with all these items in it, but the ID registers
allow for more finely grained distinctions. I wouldn't obejct if we
want to rename the V8_AES feature as V8_CRYPTO, or if
we just have a single V8_SHA bit, but I don't think it's critical
either way.

thanks
-- PMM