Re: [Xen-devel] [PATCH] libxl: use preferred syntax for network device creation with upstream qemu

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Thu, 2011-05-26 at 09:22 +0100, Markus Armbruster wrote:
> Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx> writes:
> 
> > On Wed, 2011-05-25 at 15:59 +0100, Markus Armbruster wrote:
> >> Ian Campbell <ian.campbell@xxxxxxxxxx> writes:

> >> Important optimizations like GSO or vhost-net aren't feasible with
> >> -net's VLANs (no relation to IEEE 802.1Q) .  That's why -netdev got
> >> added[*].  VLANs are still around for backward compatibility.  I hope we
> >> can get rid of them eventually.
> >> 
> >> > diff -r 8258c5a0ba35 -r 6b1fe0cba8a2 tools/libxl/libxl_dm.c
> >> > --- a/tools/libxl/libxl_dm.c     Tue May 24 16:28:07 2011 +0100
> >> > +++ b/tools/libxl/libxl_dm.c     Wed May 25 09:20:31 2011 +0100
> >> > @@ -336,11 +336,11 @@ static char ** libxl__build_device_model
> >> >                  } else {
> >> >                      ifname = vifs[i].ifname;
> >> >                  }
> >> > -                flexarray_append(dm_args, "-net");
> >> > -                flexarray_append(dm_args, libxl__sprintf(gc, 
> >> > "nic,vlan=%d,macaddr=%s,model=%s",
> >> > -                            vifs[i].devid, smac, vifs[i].model));
> >> > -                flexarray_append(dm_args, "-net");
> >> > -                flexarray_append(dm_args, libxl__sprintf(gc, 
> >> > "tap,vlan=%d,ifname=%s,script=%s",
> >> > +                flexarray_append(dm_args, "-device");
> >> > +                flexarray_append(dm_args, libxl__sprintf(gc, 
> >> > "%s,netdev=net%d,mac=%s",
> >> > +                                                         vifs[i].model, 
> >> > vifs[i].devid, smac));
> >> 
> >> You can name the device with "id=WHATEVER".  IDs are handy when you need
> >> to refer to a device, e.g. for hot-unplug with device_del.
> >
> > Sure, I just couldn't think of a better name than net<n>.
> 
> Sorry, I wasn't writing clearly, let me retry.  You're naming the host
> part of the NIC, created with -netdev.  You can also name the guest
> part, created with -device.

Oh, I see, thanks. Make sense to call it nic<n> then I guess.

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1306399775 -3600
# Node ID 7cb3b0b7f45d6272ef2c67dffd293aaf984c2ecc
# Parent  33cb7fe0d6d9f81292005e5671ebef7889c1d1ba
libxl: use preferred syntax for network device creation with upstream qemu

Markus Armbruster points out in <m3r582pzc1.fsf@xxxxxxxxxxxxxxxxxxxxx>
on qemu-devel that this is the prefered syntax going forward. Using it avoid
needlessly instantiating a qemu "vlan" and instead creates a simply host end
point and device.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Markus Armbruster <armbru@xxxxxxxxxx>

diff -r 33cb7fe0d6d9 -r 7cb3b0b7f45d tools/libxl/libxl_dm.c
--- a/tools/libxl/libxl_dm.c    Wed May 25 11:15:45 2011 +0100
+++ b/tools/libxl/libxl_dm.c    Thu May 26 09:49:35 2011 +0100
@@ -336,12 +336,16 @@ static char ** libxl__build_device_model
                 } else {
                     ifname = vifs[i].ifname;
                 }
-                flexarray_append(dm_args, "-net");
-                flexarray_append(dm_args, libxl__sprintf(gc, 
"nic,vlan=%d,macaddr=%s,model=%s",
-                            vifs[i].devid, smac, vifs[i].model));
-                flexarray_append(dm_args, "-net");
-                flexarray_append(dm_args, libxl__sprintf(gc, 
"tap,vlan=%d,ifname=%s,script=%s",
-                            vifs[i].devid, ifname, libxl_tapif_script(gc)));
+                flexarray_append(dm_args, "-device");
+                flexarray_append(dm_args,
+                                 libxl__sprintf(gc, 
"%s,id=nic%d,netdev=net%d,mac=%s",
+                                                vifs[i].model, vifs[i].devid,
+                                                vifs[i].devid, smac));
+                flexarray_append(dm_args, "-netdev");
+                flexarray_append(dm_args,
+                                 libxl__sprintf(gc, 
"type=tap,id=net%d,ifname=%s,script=%s",
+                                                vifs[i].devid, ifname,
+                                                libxl_tapif_script(gc)));
                 ioemu_vifs++;
             }
         }



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