[Qemu-devel] [PATCH] better describe -net options

[Qemu-devel] [PATCH] better describe -net options

[Brian Thomason]

[-- Attachment #1: Type: text/plain, Size: 2392 bytes --]

The manpage reflects that multiple -net user calls may be made,
but if this is done, it can cause the program to hang. Instead,
multiple -net calls can be combined into one, and this patch adds
that information to qemu-options.hx. Also, -net user may only
be used in conjunction with -net nic.  This is already implcitly
stated, but this patch makes that statement more explicit.

https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/474969
https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/453617

Signed-off-by: Brian Thomason <brian.thomason@canonical.com>
---
 qemu-options.hx |   15 +++++++++++++--
 1 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/qemu-options.hx b/qemu-options.hx
index fd50add..724f434 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -952,7 +952,8 @@ for a list of available devices for your target.

 @item -net user[,@var{option}][,@var{option}][,...]
 Use the user mode network stack which requires no administrator
-privilege to run. Valid options are:
+privilege to run. Please note that this can be used only in conjunction
with
+@option{-net nic}. Valid options are:

 @table @option
 @item vlan=@var{n}
@@ -1028,7 +1029,8 @@ the guest IP address @var{guestaddr} on guest port
@var{guestport}. If
 @var{guestaddr} is not specified, its value is x.x.x.15 (default first
address
 given by the built-in DHCP server). By specifying @var{hostaddr}, the rule
can
 be bound to a specific host interface. If no connection type is set, TCP is
-used. This option can be given multiple times.
+used. This option can not be given multiple times, but multiple rules may
+be combined.

 For example, to redirect host X11 connection from screen 1 to guest
 screen 0, use the following:
@@ -1052,6 +1054,15 @@ telnet localhost 5555
 Then when you use on the host @code{telnet localhost 5555}, you
 connect to the guest telnet server.

+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:
+
+@example
+#on the host
+qemu -net user,hostfwd=tcp:127.0.0.1:6001-:6000,hostfwd=tcp:5555-::23 [...]
+@end example
+
 @item guestfwd=[tcp]:@var{server}:@var{port}-@var{dev}
 Forward guest TCP connections to the IP address @var{server} on port
@var{port}
 to the character device @var{dev}. This option can be given multiple times.
-- 
1.6.3.3

[-- Attachment #2: Type: text/html, Size: 2805 bytes --]

Re: [Qemu-devel] [PATCH] better describe -net options

[Anthony Liguori]

[-- Attachment #1: Type: text/plain, Size: 2841 bytes --]

On 03/05/2010 03:07 PM, Brian Thomason wrote:
> The manpage reflects that multiple -net user calls may be made,
> but if this is done, it can cause the program to hang. Instead,
> multiple -net calls can be combined into one, and this patch adds
> that information to qemu-options.hx. Also, -net user may only
> be used in conjunction with -net nic.  This is already implcitly
> stated, but this patch makes that statement more explicit.

Actually, the problem is that the user created a loop.  It's actually 
valid to have something like:

-net user -net dump,file=foo.pcap -net nic

But having -net user -net user creates a loop.

Regards,

Anthony Liguori

>
> https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/474969
> https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/453617
>
> Signed-off-by: Brian Thomason <brian.thomason@canonical.com 
> <mailto:brian.thomason@canonical.com>>
> ---
>  qemu-options.hx |   15 +++++++++++++--
>  1 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index fd50add..724f434 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -952,7 +952,8 @@ for a list of available devices for your target.
>
>  @item -net user[,@var{option}][,@var{option}][,...]
>  Use the user mode network stack which requires no administrator
> -privilege to run. Valid options are:
> +privilege to run. Please note that this can be used only in 
> conjunction with
> +@option{-net nic}. Valid options are:
>
>  @table @option
>  @item vlan=@var{n}
> @@ -1028,7 +1029,8 @@ the guest IP address @var{guestaddr} on guest 
> port @var{guestport}. If
>  @var{guestaddr} is not specified, its value is x.x.x.15 (default 
> first address
>  given by the built-in DHCP server). By specifying @var{hostaddr}, the 
> rule can
>  be bound to a specific host interface. If no connection type is set, 
> TCP is
> -used. This option can be given multiple times.
> +used. This option can not be given multiple times, but multiple rules may
> +be combined.
>
>  For example, to redirect host X11 connection from screen 1 to guest
>  screen 0, use the following:
> @@ -1052,6 +1054,15 @@ telnet localhost 5555
>  Then when you use on the host @code{telnet localhost 5555}, you
>  connect to the guest telnet server.
>
> +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:
> +
> +@example
> +#on the host
> +qemu -net user,hostfwd=tcp:127.0.0.1:6001-:6000,hostfwd=tcp:5555-::23 
> [...]
> +@end example
> +
>  @item guestfwd=[tcp]:@var{server}:@var{port}-@var{dev}
>  Forward guest TCP connections to the IP address @var{server} on port 
> @var{port}
>  to the character device @var{dev}. This option can be given multiple 
> times.
> -- 
> 1.6.3.3
>


[-- Attachment #2: Type: text/html, Size: 3797 bytes --]

Re: [Qemu-devel] [PATCH] better describe -net options

[Jamie Lokier]

Anthony Liguori wrote:
> 
>    On 03/05/2010 03:07 PM, Brian Thomason wrote:
> 
>      The manpage reflects that multiple -net user calls may be made,
>      but if this is done, it can cause the program to hang. Instead,
>      multiple -net calls can be combined into one, and this patch adds
>      that information to qemu-options.hx. Also, -net user may only
>      be used in conjunction with -net nic.  This is already implcitly
>      stated, but this patch makes that statement more explicit.
> 
>    Actually, the problem is that the user created a loop.  It's actually
>    valid to have something like:
>    -net user -net dump,file=foo.pcap -net nic
>    But having -net user -net user creates a loop.

When I used -net user -net user, it didn't hang: QEMU crashed with a
stack overflow.

It crashed after a doing a successful full OS install, because
everything was fine until the first network packet.

That's not nice, even if it is user error.

-- Jamie

Re: [Qemu-devel] [PATCH] better describe -net options

[Anthony Liguori]

On 03/17/2010 11:13 AM, Jamie Lokier wrote:
> Anthony Liguori wrote:
>    
>>     On 03/05/2010 03:07 PM, Brian Thomason wrote:
>>
>>       The manpage reflects that multiple -net user calls may be made,
>>       but if this is done, it can cause the program to hang. Instead,
>>       multiple -net calls can be combined into one, and this patch adds
>>       that information to qemu-options.hx. Also, -net user may only
>>       be used in conjunction with -net nic.  This is already implcitly
>>       stated, but this patch makes that statement more explicit.
>>
>>     Actually, the problem is that the user created a loop.  It's actually
>>     valid to have something like:
>>     -net user -net dump,file=foo.pcap -net nic
>>     But having -net user -net user creates a loop.
>>      
> When I used -net user -net user, it didn't hang: QEMU crashed with a
> stack overflow.
>
> It crashed after a doing a successful full OS install, because
> everything was fine until the first network packet.
>
> That's not nice, even if it is user error.
>    

Well we should dedicate this case in the code and throw an error.

Regards,

Anthony Liguori

> -- Jamie
>