Commit 30f369f7 authored by Dariusz Stojaczyk's avatar Dariusz Stojaczyk Committed by Jim Harris
Browse files

doc/virtio: add Virtio Block doc 



I decided to use 'Virtio Block' as the title. Virtio
spec uses the same name alongside SCSI.

```
5 Device Types
[...]
 5.2 Block Device
 5.6 SCSI Host Device
```

Also added a CHANGELOG note.

Change-Id: Ie2eabd053213da776c78a8d938a621b42e6d5558
Signed-off-by: default avatarDariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/408829


Reviewed-by: default avatarDaniel Verkamp <daniel.verkamp@intel.com>
Tested-by: default avatarSPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: default avatarJohn Kariuki <John.K.Kariuki@intel.com>
Reviewed-by: default avatarPawel Wodkowski <pawelx.wodkowski@intel.com>
Reviewed-by: default avatarMaciej Szwed <maciej.szwed@intel.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
parent 13030786

CHANGELOG.md

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@@ -106,6 +106,14 @@ The persistent memory (PMDK) bdev module is now enabled using --with-pmdk instea 
--with-nvml.  This reflects the renaming of the persistent memory library from NVML to

PMDK.



### Virtio Block driver



A userspace driver for Virtio Block devices has been added. It was built on top of the

[Virtio](http://www.spdk.io/doc/virtio.html) library and can be managed similarly to

the Virtio SCSI driver. See the

[Virtio Block](http://www.spdk.io/doc/bdev.html#bdev_config_virtio_blk) reference for

more information.



## v18.01: Blobstore Thin Provisioning



### Build System

doc/bdev.md

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@@ -304,3 +304,16 @@ Virtio-SCSI devices can be removed with the following command 
`rpc.py remove_virtio_scsi_bdev VirtioScsi0`



Removing a Virtio-SCSI device will destroy all its bdevs.



# Virtio Block {#bdev_config_virtio_blk}



The Virtio-Block driver can expose an SPDK bdev from a Virtio-Block device.



Virtio-Block bdevs are constructed the same way as Virtio-SCSI ones.



`rpc.py construct_virtio_user_blk_bdev /tmp/virtio.0 VirtioBlk0 --vq-count 2 --vq-size 512`



`rpc.py construct_virtio_pci_blk_bdev 0000:01:00.0 VirtioBlk1`



Since they export only a single bdev, the Virtio-Block driver doesn't offer additional

remove/destruct RPC calls. @ref bdev_ug_delete_bdev should be used instead.

doc/virtio.md

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@@ -16,5 +16,5 @@ and context switching overhead of QEMU and guest kernel, significantly boosting 
the overall I/O performance.



This Virtio library is currently used to implement two bdev modules:

@ref bdev_config_virtio_scsi and Virtio Blk. These modules will export generic

SPDK block devices usable by any SPDK application.
 
@ref bdev_config_virtio_scsi and @ref bdev_config_virtio_blk.

These modules will export generic SPDK block devices usable by any SPDK application.