2. AESN-NI Multi Buffer Crypto Poll Mode Driver
The AESNI MB PMD (librte_pmd_aesni_mb) provides poll mode crypto driver support for utilizing Intel multi buffer library, see the white paper Fast Multi-buffer IPsec Implementations on Intel® Architecture Processors.
The AES-NI MB PMD has current only been tested on Fedora 21 64-bit with gcc.
AESNI MB PMD has support for:
- Chained mbufs are not supported.
- Only in-place is currently supported (destination address is the same as source address).
To build DPDK with the AESNI_MB_PMD the user is required to download the multi-buffer library from here and compile it on their user system before building DPDK. The latest version of the library supported by this PMD is v0.46, which can be downloaded in https://github.com/01org/intel-ipsec-mb/archive/v0.46.zip.
As a reference, the following table shows a mapping between the past DPDK versions and the Multi-Buffer library version supported by them:
|DPDK version||Multi-buffer library version|
|2.2 - 16.11||0.43 - 0.44|
In order to enable this virtual crypto PMD, user must:
- Export the environmental variable AESNI_MULTI_BUFFER_LIB_PATH with the path where the library was extracted.
- Build the multi buffer library (explained in Installation section).
- Set CONFIG_RTE_LIBRTE_PMD_AESNI_MB=y in config/common_base.
To use the PMD in an application, user must:
- Call rte_vdev_init(“crypto_aesni_mb”) within the application.
- Use –vdev=”crypto_aesni_mb” in the EAL options, which will call rte_vdev_init() internally.
The following parameters (all optional) can be provided in the previous two calls:
- socket_id: Specify the socket where the memory for the device is going to be allocated (by default, socket_id will be the socket where the core that is creating the PMD is running on).
- max_nb_queue_pairs: Specify the maximum number of queue pairs in the device (8 by default).
- max_nb_sessions: Specify the maximum number of sessions that can be created (2048 by default).
./l2fwd-crypto -l 1 -n 4 --vdev="crypto_aesni_mb,socket_id=0,max_nb_sessions=128" \ -- -p 1 --cdev SW --chain CIPHER_HASH --cipher_algo "aes-cbc" --auth_algo "sha1-hmac"
2.5. Extra notes
For AES Counter mode (AES-CTR), the library supports two different sizes for Initialization Vector (IV):
- 12 bytes: used mainly for IPSec, as it requires 12 bytes from the user, which internally are appended the counter block (4 bytes), which is set to 1 for the first block (no padding required from the user)
- 16 bytes: when passing 16 bytes, the library will take them and use the last 4 bytes as the initial counter block for the first block.