CHANGELOG: update changelog for the 20.01 release.

## v20.01: (Upcoming Release)

### bdev

A new function, `spdk_bdev_set_timeout`, has been added to set per descriptor I/O timeouts.

A new class of functions `spdk_bdev_compare*`, have been added to allow native bdev support

of block comparisons and compare-and-write.

A new class of bdev events, `SPDK_BDEV_EVENT_MEDIA_MANAGEMENT`, has been added to allow bdevs

which expose raw media to alert all I/O channels of pending media management events.

A new API was added `spdk_bdev_io_get_aux_buf` allowing the caller to request

an auxiliary buffer for its own private use. The API is used in the same manner that

`spdk_bdev_io_get_buf` is used and the length of the buffer is always the same as the

bdev_io primary buffer. 'spdk_bdev_io_put_aux_buf' frees the allocated auxiliary

buffer.

### ftl

All NVMe dependencies were removed from ftl library.

`spdk_ftl_punit_range` and `ftl_module_init_opts` structures were removed.

### nvmf

Support for custom NVMe admin command handlers and admin command passthru

in the NVMF subsystem.

It is now possible to set a custom handler for a specific NVMe admin command.

For example, vendor specific admin commands can now be intercepted by implementing

a function handling the command.

Further NVMe admin commands can be forwarded straight to an underlying NVMe bdev.

The functions `spdk_nvmf_set_custom_admin_cmd_hdlr` and `spdk_nvmf_set_passthru_admin_cmd`

in `spdk_internal/nvmf.h` expose this functionality. There is an example custom admin handler

for the NVMe IDENTIFY CTRLR in `lib/nvmf/custom_cmd_hdlr.c`. This handler gets the SN, MN, FR, IEEE, FGUID

attributes from the first NVMe drive in the NVMF subsystem and returns it to the NVMF initiator (sn and mn attributes

specified during NVMF subsystem creation RPC will be overwritten).

This handler can be enabled via the `nvmf_set_config` RPC.

Note: In a future version of SPDK, this handler will be enabled by default.

### scsi

### bdev

A new API was added `spdk_bdev_io_get_aux_buf` allowing the caller to request

an auxiliary buffer for its own private use. The API is used in the same manner that

`spdk_bdev_io_get_buf` is used and the length of the buffer is always the same as the

bdev_io primary buffer. 'spdk_bdev_io_put_aux_buf' frees the allocated auxiliary

buffer.

`spdk_scsi_lun_get_dif_ctx` now takes an additional argument of type `spdk_scsi_task`.

### sock

### thread

`spdk_thread_send_msg` now returns int indicating if the message was successfully

sent.

`spdk_thread_send_msg` now returns int indicating if the message was successfully sent.

A new function `spdk_thread_send_critical_msg`, has been added to support sending a single message from

a context that may be interrupted, e.g. a signal handler.

Two new functions, `spdk_poller_pause`, and `spdk_poller_resume`, have been added to give greater control

of pollers to the application owner.

### blobfs

incoming connections for specified target and trid. Listener is not stopped

implicitly upon destruction of a subsystem any more.

A custom NVMe admin command handler has been added which allows the user to use the real drive

attributes from one of the target NVMe drives when reporting drive attributes to the initiator.

This handler can be enabled via the `nvmf_set_config` RPC.

Note: In a future version of SPDK, this handler will be enabled by default.

The SPDK target and initiator both now include compare-and-write functionality with one caveat. If using the RDMA transport,

the target expects the initiator to send both the compare command and write command either with, or without inline data. The

SPDK initiator currently respects this requirement, but this note is included as a flag for other initiators attempting

compatibility with this version of SPDK.

### util

`spdk_pipe`, a new utility for buffering data from sockets or files for parsing

A function table, `spdk_nvme_transport_ops`, and macro, `SPDK_NVME_TRANSPORT_REGISTER`, have been added which

enable registering out of tree transports.

A new function, `spdk_nvme_ns_supports_compare`, allows a user to check whether a given namespace supports the compare

operation.

A new family of functions, `spdk_nvme_ns_compare*`, give the user access to submitting compare commands to NVMe namespaces.

A new function, `spdk_nvme_ctrlr_cmd_get_log_page_ext`, gives users more granular control over the command dwords sent in

log page requests.

### rpc

Added optional 'delay_cmd_submit' parameter to 'bdev_nvme_set_options' RPC method.

A new RPC, `bdev_zone_block_create`, enables creating an emulated zoned bdev on top of a standard block device.

An new RPC `framework_get_reactors` has been added to retrieve list of all reactors.

A new RPC, `bdev_ocssd_create`, enables creating an emulated zoned bdev on top of an Open Channel SSD.

A new RPC, `blobfs_set_cache_size`, enables managing blobfs cache size.

A new RPC, `env_dpdk_get_mem_stats`, has been added to facilitate reading DPDK related memory

consumption stats. Please see the env_dpdk section above for more details.

A new RPC, `framework_get_reactors`, has been added to retrieve a list of all reactors.

`bdev_ftl_create` now takes a `base_bdev` argument in lieu of `trtype`, `traddr`, and `punits`.

`bdev_nvme_set_options` now allows users to disable I/O submission batching with the `-d` flag

`bdev_nvme_cuse_register` now accepts a `name` parameter.

`bdev_uring_create` now takes arguments for `bdev_name` and `block_size`

`nvmf_set_config` now takes an argument to enable passthru of identify commands to base NVMe devices.

Please see the nvmf section above for more details.

### dpdk

Updated DPDK submodule to DPDK 19.11.

### env_dpdk

`spdk_env_dpdk_post_init` now takes a boolean, `legacy_mem`, as an argument.

A new function, `spdk_env_dpdk_dump_mem_stats`, prints information about the memory consumed by DPDK to a file specified by

the user. A new utility, `scripts/dpdk_mem_info.py`, wraps this function and prints the output in an easy to read way.

### event

The functions `spdk_reactor_enable_framework_monitor_context_switch()` and