Re: [dpdk-dev] [PATCH v3 1/4] bus/vmbus: add hyper-v virtual bus support

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 4/17/2018 10:53 PM, Stephen Hemminger wrote:
> From: Stephen Hemminger <stephen@networkplumber.org>
> 
> This patch adds support for an additional bus type Virtual Machine BUS
> (VMBUS) on Microsoft Hyper-V in Windows 10, Windows Server 2016
> and Azure. Most of this code was extracted from FreeBSD and some of
> this is from earlier code donated by Brocade.
> 
> Only Linux is supported at present, but the code is split
> to allow future FreeBSD and Windows support.
> 
> The bus support relies on the uio_hv_generic driver from Linux
> kernel 4.16. Multiple queue support requires additional sysfs
> interfaces which is in kernel 5.0 (a.k.a 4.17).
> 
> Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
> ---
>  MAINTAINERS                                 |   3 +
>  config/common_base                          |   5 +
>  config/common_linuxapp                      |   4 +
>  drivers/bus/Makefile                        |   1 +
>  drivers/bus/vmbus/Makefile                  |  36 ++
>  drivers/bus/vmbus/linux/Makefile            |   3 +
>  drivers/bus/vmbus/linux/vmbus_bus.c         | 355 +++++++++++++++++
>  drivers/bus/vmbus/linux/vmbus_uio.c         | 381 ++++++++++++++++++
>  drivers/bus/vmbus/private.h                 | 132 +++++++
>  drivers/bus/vmbus/rte_bus_vmbus.h           | 400 +++++++++++++++++++
>  drivers/bus/vmbus/rte_bus_vmbus_version.map |  28 ++
>  drivers/bus/vmbus/rte_vmbus_reg.h           | 344 +++++++++++++++++
>  drivers/bus/vmbus/vmbus_bufring.c           | 241 ++++++++++++
>  drivers/bus/vmbus/vmbus_channel.c           | 405 ++++++++++++++++++++
>  drivers/bus/vmbus/vmbus_common.c            | 286 ++++++++++++++
>  drivers/bus/vmbus/vmbus_common_uio.c        | 232 +++++++++++
>  mk/rte.app.mk                               |   1 +

<...>

> @@ -381,6 +381,9 @@ VDEV bus driver
>  M: Jianfeng Tan <jianfeng.tan@intel.com>
>  F: drivers/bus/vdev/
>  
> +VMBUS bus driver
> +M: Stephen Hemminger <sthemmin@microsoft.com>
> +F: drivers/bus/vmbus/

We have methods to mark APIs as experimental but not for drivers, we have put "-
EXPERIMENTAL" suffix in MAINTAINER file before, same thing can be done here.

<...>

> @@ -37,3 +37,7 @@ CONFIG_RTE_LIBRTE_DPAA2_MEMPOOL=y
>  CONFIG_RTE_LIBRTE_DPAA2_PMD=y
>  CONFIG_RTE_LIBRTE_PMD_DPAA2_EVENTDEV=y
>  CONFIG_RTE_LIBRTE_PMD_DPAA2_SEC=y
> +
> +# Hyper-V Virtual Machine bus and drivers
> +CONFIG_RTE_LIBRTE_VMBUS=y

We tend to disable the component that has external dependency, because of uuid
library dependency I believe vmbus should be disabled by default.

<...>

> +LDLIBS += -lrte_eal -lrte_mbuf -lrte_mempool -lrte_ring
> +LDLIBS += -lrte_ethdev -lrte_vmbus -luuid

-lrte_vmbus is causing build error for shared build, there is no library like
that, looks like can be dropped.

<...>

> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: BSD-3-Clause */
> +EXPERIMENTAL {
> +	global:
> +
> +	rte_vmbus_chan_close;
> +	rte_vmbus_chan_open;
> +	rte_vmbus_chan_recv;
> +	rte_vmbus_chan_recv_raw;
> +	rte_vmbus_chan_rx_empty;
> +	rte_vmbus_chan_send;
> +	rte_vmbus_chan_send_sglist;
> +	rte_vmbus_chan_signal_tx;
> +	rte_vmbus_irq_mask;
> +	rte_vmbus_irq_read;
> +	rte_vmbus_irq_unmask;
> +	rte_vmbus_map_device;
> +	rte_vmbus_max_channels;
> +	rte_vmbus_probe;
> +	rte_vmbus_probe_one;
> +	rte_vmbus_register;
> +	rte_vmbus_scan;
> +	rte_vmbus_sub_channel_index;
> +	rte_vmbus_subchan_open;
> +	rte_vmbus_unmap_device;
> +	rte_vmbus_unregister;
> +
> +	local: *;
> +};

Just to confirm, these APIs are for bus drivers, not for applications, right? If
so we already don't guarantee comptiblity in this level, perhaps adding
__experimental flag to these APIs is overkill but no harm.

<...>