On 16.10.25 13:38, Markus Armbruster wrote:
Vladimir Sementsov-Ogievskiy <[email protected]> writes:
On 16.10.25 11:48, Markus Armbruster wrote:
Vladimir Sementsov-Ogievskiy <[email protected]> writes:
This option for tap and vhost-user netdevs doesn't make sense
since long ago (10 years!), starting from commits:
1e7398a140f7a6 ("vhost: enable vhost without without MSI-X")
24f938a682d934 ("vhost user:support vhost user nic for non msi guests")
Prior these commits, to enable kernel vhost-net, or vhost-user-net for
some specific kind of guests (that don't have MSI-X support), you should
have set vhostforce=on.
Now guest type doesn't matter, all guests are equal for these
options logic.
For tap the current logic is:
vhost=on / vhost=off : vhostforce ignored, doesn't make sense
vhost unset : vhostforce counts, enabling vhost
So you may enable vhost for tap several ways:
- vhost=on
- vhostforce=on
- vhost=on + vhostforce=on
- and even vhost=on + vhostforce=off
- they are all equal.
For vhost-user we simply ignore the vhostforce option at all in the
code.
Let's finally deprecate the extra options.
Also, fix @vhostforce documentation everywhere to show the real picture,
and update vhost-user test to not use deprecated option.
Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
[...]
diff --git a/qemu-options.hx b/qemu-options.hx
index 0223ceffeb..35a70096e8 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2882,7 +2882,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
#else
"-netdev
tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
"
[,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
- "
[,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
+ " [,vhostfd=h][,vhostfds=x:y:...:z][,queues=n]\n"
" [,poll-us=n]\n"
" configure a host TAP network backend with ID 'str'\n"
" connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE
")\n"
@@ -2898,9 +2898,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
" default is disabled 'sndbuf=0' to enable flow control set
'sndbuf=1048576')\n"
" use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap
flag\n"
" use vnet_hdr=on to make the lack of IFF_VNET_HDR support an
error condition\n"
- " use vhost=on to enable experimental in kernel
accelerator\n"
- " (only has effect for virtio guests which use MSIX)\n"
- " use vhostforce=on to force vhost on for non-MSIX virtio
guests\n"
+ " use vhost=on to enable in kernel accelerator\n"
So the kernel's accelerator is no longer experimental?
Reading this, I heard the first time that vhost-net is experimental.
It's about 15 years old, and used in production. I think "experimental"
is inappropriate word here)
Just double-checking :)
The text you adjust is from 2010 (commit 82b0d80ef6a). I guess the
accelerator was experimental back then.
Mention the correction in the commit message?
Will do
--
Best regards,
Vladimir
