Re: [Qemu-devel] -net interface association behavior change in current -git.

[Rob Landley <rob@landley.net>]

On 05/12/2011 08:19 PM, Vincent Palatin wrote:
>>> First of all, as you have 2 totally separated subnets in your setup, I
>>> think your command-line should use "vlan=" parameter to isolate them,
>>> else you will end up with some random routing/broadcasting (and random
>>> tends to change over time).
>>
>> Does the kernel need some sort of vlan support compiled into it for this
>> to work, or can the kernel not care?
> 
> You don't need anything in your kernel, this is for Qemu network layer
> configuration.

Oh good.  (The kernel has a couple different VLAN config options, plus
cisco has vlan stuff in its routers...  I've been trying not to get any
of this complexity on me.)

>>> In my understanding, the Linux kernel might assign interface number
>>> depending on the order the interfaces are appearing.
>>
>> It's going in PCI bus order.  And the _interfaces_ are still happily in
>> PCI bus order both before and after this commit.  What's changing is the
>> association between interface and -net user or -net tap.
>>
>> The first one, with macaddr 11:11:11, is always eth0.  But before the
>> patch, eth0 is -net user, and after the patch eth0 is -net tap.
> 
> So, did you try the vlan parameter which is supposed to associate each
> interface with the proper thing (IMO the command line order should not
> have anything to do with it) ?

Apparently you cannot stick a vlan on -redir, and if you do the error
message is a bit funky (cannot initialize -net user).  Good to know...

Yup, that fixed it.  Thanks.

By the way, does -redir only apply to -net user?  Actually, reading qemu
--help it looks like I should be using hostfwd= but the documentation on
that is REALLY WEIRD:

  This option can not be given multiple times, but multiple rules may
  be combined.
...
  To combine two or more hostfwd rules, simply use a comma as a
  delimiter. For example, to combine the two rules mentioned in
  the examples above, use the following:

  #on the host
  qemu -net user,hostfwd=tcp:127.0.0.1:6001-:6000,hostfwd=tcp:5555-::23

Define "may not be given multiple times"...?  Oh well, specifying one of
'em seems to work.

Thanks.  As you can tell, confusion is sort of my ground state,

Rob