> On Apr 13, 2019, at 12:22 AM, Jerin Jacob Kollanukkaran <jer...@marvell.com>
> wrote:
>
>> -----Original Message-----
>> From: Yongseok Koh <ys...@mellanox.com>
>> Sent: Saturday, April 13, 2019 4:55 AM
>> To: bruce.richard...@intel.com; Jerin Jacob Kollanukkaran
>> <jer...@marvell.com>; Pavan Nikhilesh Bhagavatula
>> <pbhagavat...@marvell.com>; shah...@mellanox.com
>> Cc: dev@dpdk.org; tho...@monjalon.net; gavin...@arm.com;
>> honnappa.nagaraha...@arm.com
>> Subject: [EXT] [PATCH 5/6] build: add option for armv8 crypto extension
>>
>> CONFIG_RTE_MACHINE="armv8a"
>> +CONFIG_RTE_ENABLE_ARMV8_CRYPTO=y
>
> This approach is not scalable. Even, it is not good for BlueField as you
> you need to maintain two images.
>
> Unlike other CPU flags, arm64's crypto cpu flag is really _optional_.
> Access to crypto instructions is always at under runtime check.
> See the following in rte_armv8_pmd.c
>
>
> /* Check CPU for support for AES instruction set */
> if (!rte_cpu_get_flag_enabled(RTE_CPUFLAG_AES)) {
> ARMV8_CRYPTO_LOG_ERR(
> "AES instructions not supported by CPU");
> return -EFAULT;
> }
>
> /* Check CPU for support for SHA instruction set */
> if (!rte_cpu_get_flag_enabled(RTE_CPUFLAG_SHA1) ||
> !rte_cpu_get_flag_enabled(RTE_CPUFLAG_SHA2)) {
> ARMV8_CRYPTO_LOG_ERR(
> "SHA1/SHA2 instructions not supported by CPU");
> return -EFAULT;
> }
>
> So In order to avoid one more config flags specific to armv8 in meson and
> makefile build infra
> And avoid the need for 6/6 patch. IMO,
> # Introduce optional CPU flag scheme in eal. Treat armv8 crypto as optional
> flag
> # Skip the eal init check for optional flag.
>
> Do you see any issues with that approach?
I also thought about that approach and that was my number 1 priority. But, I had
one question came to my mind. Maybe, arm people can confirm it. Is it 100%
guaranteed that compiler never makes use of any of crypto instructions even if
there's no specific asm/intrinsic code? The crypto extension has aes, pmull,
sha1 and sha2. In case of rte_memcpy() for x86, for example, compiler may
optimize code using avx512f instructions even though it is written specifically
with avx2 intrinsics (__mm256_*) unless avx512f is disabled.
If a complier expert in arm (or anyone else) confirm it is completely
**optional**, then I'd love to take that approach for sure.
Copied dpdk-on-arm ML.
Thanks,
Yongseok
