Re: [Qemu-devel] [PATCH V6 3/5] docs: add pvrdma device documentation.

[Cornelia Huck <cohuck@redhat.com>]

On Sun,  7 Jan 2018 14:32:22 +0200
Marcel Apfelbaum <marcel@redhat.com> wrote:

> Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
> Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
> Reviewed-by: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>
> ---
>  docs/pvrdma.txt | 254 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 254 insertions(+)
>  create mode 100644 docs/pvrdma.txt

> +5. Limitations
> +==============
> +- The device obviously is limited by the Guest Linux Driver features implementation
> +  of the VMware device API.
> +- Memory registration mechanism requires mremap for every page in the buffer in order
> +  to map it to a contiguous virtual address range. Since this is not the data path
> +  it should not matter much.
> +- The device requires target page size to be the same as the host page size.
> +- QEMU cannot map guest RAM from a file descriptor if a pvrdma device is attached,
> +  so it can't work with huge pages. The limitation will be addressed in the future,
> +  however QEMU allocates Gust RAM with MADV_HUGEPAGE so if there are enough huge

s/Gust/Guest/

> +  pages available, QEMU will use them.
> +- As previously stated, migration is not supported yet, however with some hardware
> +  support can be done.