On Wed, Jan 10, 2018 at 05:18:45PM +0800, Fam Zheng wrote:
> Signed-off-by: Fam Zheng <f...@redhat.com>
> ---
> docs/qemu-block-drivers.texi | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/docs/qemu-block-drivers.texi b/docs/qemu-block-drivers.texi
> index 503c1847aa..66b27cc4f7 100644
> --- a/docs/qemu-block-drivers.texi
> +++ b/docs/qemu-block-drivers.texi
> @@ -785,6 +785,38 @@ warning: ssh server @code{ssh.example.com:22} does not
> support fsync
> With sufficiently new versions of libssh2 and OpenSSH, @code{fsync} is
> supported.
>
> +@node disk_images_nvme
> +@subsection NVMe disk images
> +
> +You can access disk images on a NVMe controller with the built-in VFIO based
> +NVMe driver. Before starting QEMU, bind the host NVMe controller to vfio-pci.
The text dives straight into vfio-pci without any explanation of this
feature. Please include something like:
NVM Express (NVMe) storage controllers can be accessed directly by a
userspace driver in QEMU. This bypasses the host kernel file system and
block layers while retaining QEMU block layer functionality, such as
block jobs, I/O throttling, etc. Disk I/O performance is typically
higher than with -drive file=/dev/sda.
> +For example:
> +
> +@example
> +# modprobe vfio-pci
> +# lspci -n -s 0000:06:0d.0
> +06:0d.0 0401: 1102:0002 (rev 08)
> +# echo 0000:06:0d.0 > /sys/bus/pci/devices/0000:06:0d.0/driver/unbind
> +# echo 1102 0002 > /sys/bus/pci/drivers/vfio-pci/new_id
> +
> +# qemu-system-x86_64 -drive
> file=nvme://@var{host}:@var{bus}:@var{slot}.@var{func}/@var{namespace}
> +@end example
> +
> +Alternative syntax using properties:
> +
> +@example
> +qemu-system-x86_64 -drive
> file.driver=nvme,file.device=@var{host}:@var{bus}:@var{slot}.@var{func},file.namespace=@var{namespace}
> +@end example
> +
> +@var{host}:@var{bus}:@var{slot}.@var{func} is the NVMe controller's PCI
> device
> +address on the host.
> +
> +@var{namespace} is the NVMe namespace number, starting from 1.
> +
> +The controller will be exclusively used by the QEMU process once started. To
> be
> +able to share storage between multiple VMs and other applications on the
> host,
> +please use file based protocols.
I suggest moving this up to the beginning in the hopes that people will
read it before asking questions on IRC or qemu-devel :).
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