Changeset
net/hub.c       | 4 ++++
qemu-options.hx | 6 ++++--
2 files changed, 8 insertions(+), 2 deletions(-)
Git apply log
Switched to a new branch '1495613046-6430-1-git-send-email-thuth@redhat.com'
Applying: net: Mark the 'hubport' netdev as deprecated
To https://github.com/patchew-project/qemu
 * [new tag]         patchew/1495613046-6430-1-git-send-email-thuth@redhat.com -> patchew/1495613046-6430-1-git-send-email-thuth@redhat.com
Test passed: s390x

loading

Test passed: docker

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Test passed: checkpatch

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[Qemu-devel] [PATCH] net: Mark the 'hubport' netdev as deprecated
Posted by Thomas Huth, 59 weeks ago
The 'hubport' netdev is closely tied to the 'vlan' concept which
has been marked as deprecated in commit a2dbe1356faff3cb6 already.
Thus we should also mark the hubport netdevs as deprecated to make
the remaining users aware that they should not use this anymore.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 net/hub.c       | 4 ++++
 qemu-options.hx | 6 ++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/net/hub.c b/net/hub.c
index 32d8cf5..85bd5bc 100644
--- a/net/hub.c
+++ b/net/hub.c
@@ -13,6 +13,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 #include "monitor/monitor.h"
 #include "net/net.h"
 #include "clients.h"
@@ -286,6 +287,9 @@ int net_init_hubport(const Netdev *netdev, const char *name,
 {
     const NetdevHubPortOptions *hubport;
 
+    error_report("hubports are deprecated and will be removed in a "
+                 "future release");
+
     assert(netdev->type == NET_CLIENT_DRIVER_HUBPORT);
     assert(!peer);
     hubport = &netdev->u.hubport;
diff --git a/qemu-options.hx b/qemu-options.hx
index dc1a48a..efb555c 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1810,7 +1810,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
     "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
     "                configure a vhost-user network, backed by a chardev 'dev'\n"
     "-netdev hubport,id=str,hubid=n\n"
-    "                configure a hub port on QEMU VLAN 'n'\n", QEMU_ARCH_ALL)
+    "                configure a hub port on QEMU VLAN 'n' (deprecated)\n", QEMU_ARCH_ALL)
 DEF("net", HAS_ARG, QEMU_OPTION_net,
     "-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
     "                old way to create a new NIC and connect it to VLAN 'n'\n"
@@ -2239,7 +2239,9 @@ Create a hub port on QEMU "vlan" @var{hubid}.
 
 The hubport netdev lets you connect a NIC to a QEMU "vlan" instead of a single
 netdev.  @code{-net} and @code{-device} with parameter @option{vlan} create the
-required hub automatically.
+required hub automatically. Note that the "vlan" concept and thus the hubport
+option, too, are considered as deprecated and might be removed in a future
+release of QEMU.
 
 @item -netdev vhost-user,chardev=@var{id}[,vhostforce=on|off][,queues=n]
 
-- 
1.8.3.1


Re: [Qemu-devel] [PATCH] net: Mark the 'hubport' netdev as deprecated
Posted by Thomas Huth, 42 weeks ago
On 24.05.2017 10:04, Thomas Huth wrote:
> The 'hubport' netdev is closely tied to the 'vlan' concept which
> has been marked as deprecated in commit a2dbe1356faff3cb6 already.
> Thus we should also mark the hubport netdevs as deprecated to make
> the remaining users aware that they should not use this anymore.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  net/hub.c       | 4 ++++
>  qemu-options.hx | 6 ++++--
>  2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/net/hub.c b/net/hub.c
> index 32d8cf5..85bd5bc 100644
> --- a/net/hub.c
> +++ b/net/hub.c
> @@ -13,6 +13,7 @@
>   */
>  
>  #include "qemu/osdep.h"
> +#include "qemu/error-report.h"
>  #include "monitor/monitor.h"
>  #include "net/net.h"
>  #include "clients.h"
> @@ -286,6 +287,9 @@ int net_init_hubport(const Netdev *netdev, const char *name,
>  {
>      const NetdevHubPortOptions *hubport;
>  
> +    error_report("hubports are deprecated and will be removed in a "
> +                 "future release");
> +
>      assert(netdev->type == NET_CLIENT_DRIVER_HUBPORT);
>      assert(!peer);
>      hubport = &netdev->u.hubport;
> diff --git a/qemu-options.hx b/qemu-options.hx
> index dc1a48a..efb555c 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1810,7 +1810,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
>      "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
>      "                configure a vhost-user network, backed by a chardev 'dev'\n"
>      "-netdev hubport,id=str,hubid=n\n"
> -    "                configure a hub port on QEMU VLAN 'n'\n", QEMU_ARCH_ALL)
> +    "                configure a hub port on QEMU VLAN 'n' (deprecated)\n", QEMU_ARCH_ALL)
>  DEF("net", HAS_ARG, QEMU_OPTION_net,
>      "-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
>      "                old way to create a new NIC and connect it to VLAN 'n'\n"
> @@ -2239,7 +2239,9 @@ Create a hub port on QEMU "vlan" @var{hubid}.
>  
>  The hubport netdev lets you connect a NIC to a QEMU "vlan" instead of a single
>  netdev.  @code{-net} and @code{-device} with parameter @option{vlan} create the
> -required hub automatically.
> +required hub automatically. Note that the "vlan" concept and thus the hubport
> +option, too, are considered as deprecated and might be removed in a future
> +release of QEMU.
>  
>  @item -netdev vhost-user,chardev=@var{id}[,vhostforce=on|off][,queues=n]
>  
> 

ping?

 Thomas

Re: [Qemu-devel] [PATCH] net: Mark the 'hubport' netdev as deprecated
Posted by Daniel P. Berrange, 42 weeks ago
On Wed, Sep 20, 2017 at 09:45:59AM +0200, Thomas Huth wrote:
> On 24.05.2017 10:04, Thomas Huth wrote:
> > The 'hubport' netdev is closely tied to the 'vlan' concept which
> > has been marked as deprecated in commit a2dbe1356faff3cb6 already.
> > Thus we should also mark the hubport netdevs as deprecated to make
> > the remaining users aware that they should not use this anymore.
> > 
> > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > ---
> >  net/hub.c       | 4 ++++
> >  qemu-options.hx | 6 ++++--
> >  2 files changed, 8 insertions(+), 2 deletions(-)

Needs to include a update to the qemu-doc.texi  "Deprecated features"
appendix

Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|

Re: [Qemu-devel] [PATCH] net: Mark the 'hubport' netdev as deprecated
Posted by Paolo Bonzini, 42 weeks ago
On 20/09/2017 09:45, Thomas Huth wrote:
> On 24.05.2017 10:04, Thomas Huth wrote:
>> The 'hubport' netdev is closely tied to the 'vlan' concept which
>> has been marked as deprecated in commit a2dbe1356faff3cb6 already.
>> Thus we should also mark the hubport netdevs as deprecated to make
>> the remaining users aware that they should not use this anymore.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>

What is the replacement for VLANs?

The point of hub/hubport was to implement this without needing
special-casing of VLANs everywhere in the net/ directory.  VLANs remain
messy in terms of command-line expression for -net, but that's where the
problems end.

In fact, while there are some uses of VLANs that have been replaced by
filters, VLANs are still needed to place 2 NICs to be on the same guest
network without using a host bridge.  This should be a supported use
case for e.g. L2TP backends, and it can be important for users that
don't have the ability to configure a host bridge.

In addition, depending on how you read the warning in commit a2dbe1356,
this patch could be deprecating the exact replacement that you're
suggesting in the warning.

Rather than deprecating hubport, we need a mechanism to define a hubport
for the back-end side.  For example:

   -netdev l2tp,...,id=l2tp-backend
   -netdev hubport,hubid=0,netdev=l2tp-backend,id=l2tp-hub
   -netdev hubport,hubid=0,id=nic0 -device virtio-net-pci,netdev=nic0
   -netdev hubport,hubid=0,id=nic1 -device virtio-net-pci,netdev=nic1

This would normalize the topology

   NIC      NIC      L2TP
    |        |        |
   hubport  hubport   |
    |        |        |
    '--------'--------'-------- hub

to

   NIC      NIC      L2TP
    |        |        |
   hubport  hubport  hubport
    |        |        |
    '--------'--------'-------- hub

and would let us drop vlan from the command-line options.  Even
immediately in 2.11.

(Also, the reasoning in commit a2dbe1356 seems backwards, what's wrong
with connecting two NICs with a cross cable?  If you can do it with
physical hardware, you ought to be able to do it in QEMU).

And in any case, this is certainly not a trivial patch!

Paolo

>> ---
>>  net/hub.c       | 4 ++++
>>  qemu-options.hx | 6 ++++--
>>  2 files changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/hub.c b/net/hub.c
>> index 32d8cf5..85bd5bc 100644
>> --- a/net/hub.c
>> +++ b/net/hub.c
>> @@ -13,6 +13,7 @@
>>   */
>>  
>>  #include "qemu/osdep.h"
>> +#include "qemu/error-report.h"
>>  #include "monitor/monitor.h"
>>  #include "net/net.h"
>>  #include "clients.h"
>> @@ -286,6 +287,9 @@ int net_init_hubport(const Netdev *netdev, const char *name,
>>  {
>>      const NetdevHubPortOptions *hubport;
>>  
>> +    error_report("hubports are deprecated and will be removed in a "
>> +                 "future release");
>> +
>>      assert(netdev->type == NET_CLIENT_DRIVER_HUBPORT);
>>      assert(!peer);
>>      hubport = &netdev->u.hubport;
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index dc1a48a..efb555c 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -1810,7 +1810,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
>>      "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
>>      "                configure a vhost-user network, backed by a chardev 'dev'\n"
>>      "-netdev hubport,id=str,hubid=n\n"
>> -    "                configure a hub port on QEMU VLAN 'n'\n", QEMU_ARCH_ALL)
>> +    "                configure a hub port on QEMU VLAN 'n' (deprecated)\n", QEMU_ARCH_ALL)
>>  DEF("net", HAS_ARG, QEMU_OPTION_net,
>>      "-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
>>      "                old way to create a new NIC and connect it to VLAN 'n'\n"
>> @@ -2239,7 +2239,9 @@ Create a hub port on QEMU "vlan" @var{hubid}.
>>  
>>  The hubport netdev lets you connect a NIC to a QEMU "vlan" instead of a single
>>  netdev.  @code{-net} and @code{-device} with parameter @option{vlan} create the
>> -required hub automatically.
>> +required hub automatically. Note that the "vlan" concept and thus the hubport
>> +option, too, are considered as deprecated and might be removed in a future
>> +release of QEMU.
>>  
>>  @item -netdev vhost-user,chardev=@var{id}[,vhostforce=on|off][,queues=n]
>>  
>>
> 
> ping?
> 
>  Thomas
> 


Re: [Qemu-devel] [PATCH] net: Mark the 'hubport' netdev as deprecated
Posted by Thomas Huth, 42 weeks ago
On 20.09.2017 13:07, Paolo Bonzini wrote:
> On 20/09/2017 09:45, Thomas Huth wrote:
>> On 24.05.2017 10:04, Thomas Huth wrote:
>>> The 'hubport' netdev is closely tied to the 'vlan' concept which
>>> has been marked as deprecated in commit a2dbe1356faff3cb6 already.
>>> Thus we should also mark the hubport netdevs as deprecated to make
>>> the remaining users aware that they should not use this anymore.
>>>
>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
> 
> What is the replacement for VLANs?
> 
> The point of hub/hubport was to implement this without needing
> special-casing of VLANs everywhere in the net/ directory.  VLANs remain
> messy in terms of command-line expression for -net, but that's where the
> problems end.

The QEMU "VLAN"s are a complete PITA for the users, they are causing
confusion (e.g. https://bugs.launchpad.net/qemu/+bug/658904) and
mis-configurations (see e.g.
http://lists.gnu.org/archive/html/qemu-discuss/2017-08/msg00031.html).
So I hope you agree that we should get rid of this "vlan" stuff in QEMU
(no matter whether we continue to provide some kind of "hub" or "switch"
instead or completely remove it).

> In fact, while there are some uses of VLANs that have been replaced by
> filters, VLANs are still needed to place 2 NICs to be on the same guest
> network without using a host bridge.  This should be a supported use
> case for e.g. L2TP backends, and it can be important for users that
> don't have the ability to configure a host bridge.

I don't think that anybody really wants to connect two NICs of one
machine to a *hub* - all the network traffic of one NIC will go to the
other, too! That might only make sense if you want to do some basic
network driver tests in your guest, but for every normal OS, this is
nonsense. You normally are also not doing this with real hardware (note
that we're talking about hubs, not switches!).

> Rather than deprecating hubport, we need a mechanism to define a hubport
> for the back-end side.  For example:
> 
>    -netdev l2tp,...,id=l2tp-backend
>    -netdev hubport,hubid=0,netdev=l2tp-backend,id=l2tp-hub
>    -netdev hubport,hubid=0,id=nic0 -device virtio-net-pci,netdev=nic0
>    -netdev hubport,hubid=0,id=nic1 -device virtio-net-pci,netdev=nic1
> 
> This would normalize the topology
> 
>    NIC      NIC      L2TP
>     |        |        |
>    hubport  hubport   |
>     |        |        |
>     '--------'--------'-------- hub
> 
> to
> 
>    NIC      NIC      L2TP
>     |        |        |
>    hubport  hubport  hubport
>     |        |        |
>     '--------'--------'-------- hub
> 
> and would let us drop vlan from the command-line options.  Even
> immediately in 2.11.

While that looks at least way more logical than the "vlan" parameter, I
really doubt that we need a *hub* within QEMU. Emulating a switch might
make at least a little bit more sense ... but still, do we really need
this? Do you have any real world example where somebody is using QEMU
for a configuration like this?

 Thomas


PS: Or are you just afraid that we might finally get rid of the short
"-net nic -net tap" syntax, which is way easier to type than its -netdev
equivalent? Well, I'd say that's a different topic, and we should come
up with a new convenience option instead before we remove the old one.

Re: [Qemu-devel] [PATCH] net: Mark the 'hubport' netdev as deprecated
Posted by Paolo Bonzini, 42 weeks ago
On 20/09/2017 13:57, Thomas Huth wrote:
> On 20.09.2017 13:07, Paolo Bonzini wrote:
>> On 20/09/2017 09:45, Thomas Huth wrote:
>>> On 24.05.2017 10:04, Thomas Huth wrote:
>>>> The 'hubport' netdev is closely tied to the 'vlan' concept which
>>>> has been marked as deprecated in commit a2dbe1356faff3cb6 already.
>>>> Thus we should also mark the hubport netdevs as deprecated to make
>>>> the remaining users aware that they should not use this anymore.
>>>>
>>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>>
>> What is the replacement for VLANs?
>>
>> The point of hub/hubport was to implement this without needing
>> special-casing of VLANs everywhere in the net/ directory.  VLANs remain
>> messy in terms of command-line expression for -net, but that's where the
>> problems end.
> 
> The QEMU "VLAN"s are a complete PITA for the users, they are causing
> confusion (e.g. https://bugs.launchpad.net/qemu/+bug/658904) and
> mis-configurations (see e.g.
> http://lists.gnu.org/archive/html/qemu-discuss/2017-08/msg00031.html).
> So I hope you agree that we should get rid of this "vlan" stuff in QEMU
> (no matter whether we continue to provide some kind of "hub" or "switch"
> instead or completely remove it).
> 
>> In fact, while there are some uses of VLANs that have been replaced by
>> filters, VLANs are still needed to place 2 NICs to be on the same guest
>> network without using a host bridge.  This should be a supported use
>> case for e.g. L2TP backends, and it can be important for users that
>> don't have the ability to configure a host bridge.
> 
> I don't think that anybody really wants to connect two NICs of one
> machine to a *hub* - all the network traffic of one NIC will go to the
> other, too! That might only make sense if you want to do some basic
> network driver tests in your guest, but for every normal OS, this is
> nonsense. You normally are also not doing this with real hardware (note
> that we're talking about hubs, not switches!).

Whether it's a hub or switch is an implementation detail; currently QEMU
supports hubs, which is probably a good idea because this _is_ a
somewhat fringe use and performance isn't super important.

> While that looks at least way more logical than the "vlan" parameter, I
> really doubt that we need a *hub* within QEMU. Emulating a switch might
> make at least a little bit more sense ... but still, do we really need
> this? Do you have any real world example where somebody is using QEMU
> for a configuration like this?

If you have two NICs and SLIRP, for example, the two NICs will be in
entirely different subnets and cannot talk to each other without setting
up something like proxy ARP in the guest.

> PS: Or are you just afraid that we might finally get rid of the short
> "-net nic -net tap" syntax, which is way easier to type than its -netdev
> equivalent? Well, I'd say that's a different topic, and we should come
> up with a new convenience option instead before we remove the old one.

No, this is a different topic.  It's just about hubs and providing a
replacement for these four lines of net/net.c:

     if (netdev->type != NET_CLIENT_DRIVER_NIC ||
         !opts->u.nic.has_netdev) {
         peer = net_hub_add_port(net->has_vlan ? net->vlan : 0, NULL);
     }

Regarding "-net", a replacement for "-net nic,vlan=0 -net tap,vlan=0
-net nic,vlan=1 -net tap,vlan=1" (where the connection is point-to-point
and vlans are pointless) already exists using "-net nic,netdev".  If you
removed VLANs then "-net nic -net tap" could be kept as syntactic sugar,
but "-net nic -net nic -net tap" would not.  Instead, you'd have to
declare the three hubports manually and use "-net nic,netdev=hubportN".

Paolo