On Fri, 23 Aug 2019 16:39:40 +0100
Stefan Hajnoczi <> wrote:
> Describe how shared memory region ID 0 is the DAX window and how
> FUSE_SETUPMAPPING maps file ranges into the window.
>
> Signed-off-by: Stefan Hajnoczi <>
> ---
> The FUSE_SETUPMAPPING message is part of the virtio-fs Linux patches:
> https://gitlab.com/virtio-fs/linux/blob/virtio-fs/include/uapi/linux/fuse.h
>
> v7:
> * Clarify that the DAX Window is optional and can be used together with
> FUSE_READ/FUSE_WRITE requests [Cornelia]
> v6:
> * Document timing side-channel attacks [Michael]
> ---
> virtio-fs.tex | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 66 insertions(+)
(...)
> +\drivernormative{\paragraph}{Device Operation: DAX Window}{Device Types / File System Device / Device Operation / Device Operation: DAX Window}
> +
> +The driver SHOULD be prepared to find shared memory region ID 0 absent and fall back to FUSE\_READ and FUSE\_WRITE requests.
> +
> +The driver MAY use FUSE\_READ and FUSE\_WRITE requests and also access file contents through the DAX Window.
"The driver MAY both use FUSE_READ and FUSE_WRITE requests and access
file contents through the DAX Window." ?
Not sure whether that makes it clearer that it is fine to use a
combination of both methods.
> +
> +The driver MUST NOT access DAX window areas that have not been mapped.
> +
Otherwise, looks good.
