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Re: [PATCH] qemu-options.hx: 9p: clarify -virtfs vs. -fsdev
From: |
Cornelia Huck |
Subject: |
Re: [PATCH] qemu-options.hx: 9p: clarify -virtfs vs. -fsdev |
Date: |
Tue, 31 Mar 2020 17:27:27 +0200 |
On Tue, 31 Mar 2020 15:23:38 +0200
Christian Schoenebeck <address@hidden> wrote:
> The docs are ambiguous about the difference (or actually their
> equality) between options '-virtfs' vs. '-fsdev'. So clarify that
> '-virtfs' is actually just a convenience shortcut for its
> generalized form '-fsdev' in conjunction with '-device virtio-9p-pci'.
>
> And as we're at it, also be a bit more descriptive what 9pfs is
> actually used for.
>
> Signed-off-by: Christian Schoenebeck <address@hidden>
> ---
> qemu-options.hx | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 962a5ebaa6..fd3830c6cd 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1542,9 +1542,17 @@ SRST
> ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag
> [,writeout=writeout][,readonly]``
> \
> ``-virtfs synth,mount_tag=mount_tag``
> - Define a new filesystem device and expose it to the guest using a
> - virtio-9p-device. The general form of a Virtual File system
> - pass-through options are:
> + Define a new virtual filesystem device and expose it to the guest using
> + a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain
> + directory on host is made directly accessible by guest as a pass-through
> + file system by using the 9P network protocol for communication between
> + host and guests, if desired even accessible, shared by several guests
> + simultaniously.
> +
> + Note that ``-virtfs`` is actually just a convenience shortcut for its
> + generalized form ``-fsdev -device virtio-9p-pci``.
Huh. This prompted me to try this on s390, and it actually creates a
virtio-9p-pci device there as well, not a virtio-9p-ccw device. A bit
surprising; but I don't see 9p used much (if at all) on s390 anyway.
> +
> + The general form of pass-through file system options are:
>
> ``local``
> Accesses to the filesystem are done by QEMU.
Good to see this spelled out:
Acked-by: Cornelia Huck <address@hidden>