On 2015/05/26 11:46, Tetsuya Mukawa wrote: > Hi Eric, > > On 月, 2015-05-25 at 16:11 -0600, Eric Blake wrote: >> On 05/25/2015 01:28 AM, Tetsuya Mukawa wrote: >>> This patch adds 'backend_features' option for vhost-user backends. >>> If this option is specified, QEMU assumes vhost-user backends support >>> the features specified by user, and QEMU can start without vhost-user >>> backend. >>> >>> Here are examples. >>> * QEMU is configured as vhost-user client. >>> -chardev socket,id=chr0,path=/tmp/sock,reconnect=3 \ >>> -netdev >>> vhost-user,id=net0,chardev=chr0,vhostforce,backend_features=0x68000 \ >>> -device virtio-net-pci,netdev=net0 \ >>> >>> * QEMU is configured as vhost-user server. >>> -chardev socket,id=chr0,path=/tmp/sock,server,nowait \ >>> -netdev >>> vhost-user,id=net0,chardev=chr0,vhostforce,backend_features=0x68000 \ >>> -device virtio-net-pci,netdev=net0 \ >>> >>> To know vhost-user backend features that the backend expects, please >>> specify 0xffffffff as backend_features, then invoke QEMU and check error log >>> like below. >>> >>> Lack of backend features. Expected 0xffffffff, but receives 0x68000 >>> >>> Above log indicates the backend features QEMU should be passed. >>> >>> Signed-off-by: Tetsuya Mukawa <muk...@igel.co.jp> >>> --- >>> +++ b/qapi-schema.json >>> @@ -2243,6 +2243,8 @@ >>> # >>> # @queues: #optional number of queues to be created for multiqueue capable >>> tap >>> # >>> +# @backend_features: #optional feature flag to support vhost user backend >> Missing a (since 2.4) designation. >> >> New interfaces should prefer - over _, but I see that you are consistent >> with vnet_hder already in this struct so it is okay. >> >>> +# >>> # Since 1.2 >>> ## >>> { 'struct': 'NetdevTapOptions', >>> @@ -2259,7 +2261,8 @@ >>> '*vhostfd': 'str', >>> '*vhostfds': 'str', >>> '*vhostforce': 'bool', >>> - '*queues': 'uint32'} } >>> + '*queues': 'uint32', >>> + '*backend_features':'uint64'} } >> Ewww. Making users figure out what integers to pass is NOT user >> friendly. Better would be an enum type, and make the parameter an >> optional array of enum values. > Thanks for your comments. > I guess below may be good example. Is this same as your suggestion? > > virtio-net-pci,netdev=hostnet3,id=net3,gso=off,guest_tso4=off,guest_tso6=off > > So I will improve 'backend-features' like below. > > backend-features=gso=off,guest_tso4=off,guest_tso6=off > > Also I will fix 'qapi-schema.json' to work like above.
I seems it's impossible to implement like above. I may need to implement like below. virtio-net-pci,netdev=hostnet3,id=net3,backend_gso=on,backend_guest_tso4=on,backend_guest_tso6=on Tetsuya >>> >>> ## >>> # @NetdevSocketOptions >>> @@ -2444,12 +2447,15 @@ >>> # >>> # @vhostforce: #optional vhost on for non-MSIX virtio guests (default: >>> false). >>> # >>> +# @backend_features: #optional feature flag to support vhost user backend >>> (default: 0). >>> +# >> Long line. Please wrap to fit within 80 columns. Missing (since 2.4) >> deisgnation. > I will fix it in v2 patch. > >> Again, I don't like making users know a raw integer; an >> enum type would be better. >> >>> # Since 2.1 >>> ## >>> { 'struct': 'NetdevVhostUserOptions', >>> 'data': { >>> 'chardev': 'str', >>> - '*vhostforce': 'bool' } } >>> + '*vhostforce': 'bool', >>> + '*backend_features': 'uint64' } } >> This struct has no pre-existing _, so the name 'backend-features' is nicer. >> > Also I will fix it. > > Regards, > Tetsuya > >