Re: [Qemu-devel] tun/tap networking: patch for existing tun
no vde for windows hosts :( On 10/3/05, Jean-Christian de Rivaz [EMAIL PROTECTED] wrote: Christian MICHON a écrit : to do so, does that mean we would need to launch a 1st qemu instance which would contain the dhcp server, and next qemu instances would connect to it ? if so, 'qemu -server' and 'qemu -client -connect_to server' could be useful... As I understand and with what I know, you can do that now using a virtual network (VDE for example). What matter is that fact that two qemu instances are connected on the same network. DHCP protocol (like any others netowrk protocol) is over that network and is not visible to qemu. To do what you wants, you have to use to different operating system image, one that contains a DHCP server, and the second that contain a DHCP client. 1) create a virtual switch: vde_switch -s /tmp/my_switch.ctl 2) start a virtual server: vdeq -s /tmp/my_switch.ctl qemu-softmmu -hda dhcp-server.bin [...] 3) start a virtual client: vdeq -s /tmp/my_switch.ctl qemu-softmmu -hda dhcp-client.bin [...] -- Jean-Christian de Rivaz ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel -- Christian ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
Christian MICHON a écrit : no vde for windows hosts :( Have you tryed ? Because the VDE code don't interract to mutch with the system (only require POSIX OS) and contains a lot of win32 test as you can see in the attachement. But there is no document how to compile that. Since there are win32 test into the configure, I think this will require Cygwin tools. -- Jean-Christian de Rivaz ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
I'd argue that it should be -tap or -tuntap instead of -tun, since using tun would confuse users who knew the distinction between tun devices and tap devices. Ok for -tuntap long option. Can I propose -t for a short option ? I'm not sure if a -vde option is necessary or a good idea, though. We might want to keep a -socket-fd option around for the really technical people who do funny things like that. (imho -tun-fd is badly named since it doesn't require a tun/tap fd, it works with any type of file descriptor.) So -tun-fd will be renamed -socket-fd. The idea of the -vde option is to have in parameter the VDE socket (default to /tmp/vde.ctl) an act like vde_plug so it don't need any other code to work. Just start a vde_switch and as many qemu -vde you wants to create a complete virtual nework (1 switch and n hosts). -tun-fd (or -socket-fd) should probably be kept around for really specialized applications (and the geeks who know how to use them). We should have options that adaquately cover everything in normal use, of course. Yes, this is the good way to make it, I agree. So an open question: is the -tun and -vde options a good idea to cleanup the network interface options ? To be clear, I don't propose to remove option at this point, but just to make qemu more easy to use for simple and most common setup. Actually, they might just add to the clutter. -dummy-net, -user-net, -nics, -macaddr, etc. It would be even worse if not for the fact that Fabrice has refused to incorporate many networking patches (silently, as usual). The fact that we don't know what Fabrice think about this subjet is a problem. Only Fabrice can commit to the qemu CVS as I understand. I hope Fabrice read this list and can provids to us usefull informations on how to make the patch to get it accepted. So while we're at it, we should redesign the interface for qemu. For each nic, we'd have -net type[,macaddr] where type is tap or user or dummy and the macaddr is an (optional) parameter that replaces -macaddr. Number of nics would depend on number of -net options, with none meaning either no nics or one nic defaulting to tap (or user if tap isn't available). For the tap type we could have a 3rd optional parameter for the name, e.g. -net tap,macaddr,name (with name defaulting to tapX if its not specified). This is an other work, but why not ? I think that a syntax like -net type[:macaddr][,arg[,arg[...]]] is more usefull, since the MAC addresse of the TAP devices is not alway specified as it can be set randomly by the Linux kernel (with possible collision see code in include/linux/etherdevice.h). The advantage of your proposition is that it make more easy to add new type of network device like VDE. This enable to possibility to use a socket-fd type to make everyone happy. In case of this new interface, will network script still needed. If yes, how should we handle them in the new option syntax ? -- Jean-Christian de Rivaz ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Mon, Oct 03, 2005 at 11:46:57AM +0200, Jean-Christian de Rivaz wrote: Ok for -tuntap long option. Can I propose -t for a short option ? Makes sense. The idea of the -vde option is to have in parameter the VDE socket (default to /tmp/vde.ctl) an act like vde_plug so it don't need any other code to work. Just start a vde_switch and as many qemu -vde you wants to create a complete virtual nework (1 switch and n hosts). One potential issue is that the vde code is under the GPL, while qemu (at least the part that we're talking about) is under the BSD license. I'm not sure if use of VDE is common enough to justify having special code for it in qemu anyways. This is an other work, but why not ? I think that a syntax like -net type[:macaddr][,arg[,arg[...]]] is more usefull, since the MAC addresse of the TAP devices is not alway specified as it can be set randomly by the Linux kernel (with possible collision see code in include/linux/etherdevice.h). The macaddr sets the mac address of the guest nic that qemu provides. I do not know if it is possible to set a tap device's mac address on creation but if it is possible then I agree that it would be a useful parameter. The advantage of your proposition is that it make more easy to add new type of network device like VDE. This enable to possibility to use a socket-fd type to make everyone happy. In case of this new interface, will network script still needed. If yes, how should we handle them in the new option syntax ? Network scripts will only be needed for tuntap devices that are created by qemu, same as now. The -n script thing (defaulting to /etc/qemu-ifup) should continue to work fine. The parameters that we choose to pass to the script will be a separate issue. My vote is qemu-ifup tapname macaddr (with macaddr being what was specified on the -net command line or the appropriate default). The fact that we don't know what Fabrice think about this subjet is a problem. Only Fabrice can commit to the qemu CVS as I understand. I hope Fabrice read this list and can provids to us usefull informations on how to make the patch to get it accepted. Actually a lot of the issues have been discussed before. The -net syntax was his idea I believe. Once Fabrice makes his opinion known, he generally will keep quiet until code appears. Once the patch is written, then we can start asking Fabrice for changes or improvements needed to make the patch commitable (as then we'll actually have something substantial for him to look at). -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Mon, 3 Oct 2005, Jean-Christian de Rivaz wrote: The idea of the -vde option is to have in parameter the VDE socket (default to /tmp/vde.ctl) an act like vde_plug so it don't need any other code to work. Just start a vde_switch and as many qemu -vde you wants to create a complete virtual nework (1 switch and n hosts). Or in line with the earlier proposal of a -net option: -net vde,socket=/path/to/vde.ctl,group=xxx where socket defaults to /tmp/vde.ctl and group defaults to 0 if not specified. I think that a syntax like -net type[:macaddr][,arg[,arg[...]]] is more usefull, since the MAC addresse of the TAP devices is not alway specified as it can be set randomly by the Linux kernel (with possible collision see code in include/linux/etherdevice.h). The MAC of the TUN/TAP device on the host side is a completely different thing and is the MAC the HOST should use on that virtual ethernet. What the option to QEMU specifies is the MAC QEMU should use. In case of this new interface, will network script still needed. If yes, how should we handle them in the new option syntax ? -net ...,script=/path/to/script Regards Henrik ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Sun, 2 Oct 2005, Jim C. Brown wrote: So while we're at it, we should redesign the interface for qemu. For each nic, we'd have -net type[,macaddr] where type is tap or user or dummy and the macaddr is an (optional) parameter that replaces -macaddr. Number of nics would depend on number of -net options, with none meaning either no nics or one nic defaulting to tap (or user if tap isn't available). The proposal by Fabrice looks better to me -net usernet,macaddr=00:11:a:0:2:19 -net tunfd=10,macaddr=00:11:a:0:1:19 this way the syntax can easily be extended with new options as needed, and the exact order of things is not important (you just specify the net parameters as needed). Only objection is that for the tunfd case I would use -net tap,fd=10,macaddr=... For the tap type we could have a 3rd optional parameter for the name, e.g. -net tap,macaddr,name (with name defaulting to tapX if its not specified). What about this: -net tap,ifname=qemu0,macaddr=... Regards Henrik ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
Jim C. Brown a écrit :
The idea of the -vde option is to have in parameter the VDE socket
(default to /tmp/vde.ctl) an act like vde_plug so it don't need any
other code to work. Just start a vde_switch and as many qemu -vde
you wants to create a complete virtual nework (1 switch and n hosts).
One potential issue is that the vde code is under the GPL, while qemu (at
least the part that we're talking about) is under the BSD license.
Ok. that a point to look at. The methode used to connect to a VDE is
simple, and it should be relatively a small work to rewrite a new code
that do that under the BSD license.
I'm not sure if use of VDE is common enough to justify having special code for
it in qemu anyways.
It's matter to make the use of VDE easy for the users. I think it will
become more common that some others options for advancer users. Product
like vmware offert a private network setting in standard.
I think that a syntax like -net type[:macaddr][,arg[,arg[...]]] is
more usefull, since the MAC addresse of the TAP devices is not alway
specified as it can be set randomly by the Linux kernel (with possible
collision see code in include/linux/etherdevice.h).
The macaddr sets the mac address of the guest nic that qemu provides. I do
not know if it is possible to set a tap device's mac address on creation
but if it is possible then I agree that it would be a useful parameter.
From Linux drivers/net/tun.c
static int tun_chr_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
[...]
case SIOCSIFHWADDR:
/** Set the character device's hardware address. This
is used when
* filtering packets being sent from the network device
to the character
* device. */
memcpy(tun-dev_addr, ifr.ifr_hwaddr.sa_data,
min(sizeof ifr.ifr_hwaddr.sa_data,
sizeof tun-dev_addr));
DBG(KERN_DEBUG %s: set hardware address:
%x:%x:%x:%x:%x:%x\n,
tun-dev-name,
tun-dev_addr[0], tun-dev_addr[1],
tun-dev_addr[2],
tun-dev_addr[3], tun-dev_addr[4],
tun-dev_addr[5]);
return 0;
Giving this code, I think the answare is yes: it's possible to set the
MAC addresse of a TUN/TAP device.
In case of this new interface, will network script still needed. If yes,
how should we handle them in the new option syntax ?
Network scripts will only be needed for tuntap devices that are created by
qemu, same as now. The -n script thing (defaulting to /etc/qemu-ifup) should
continue to work fine.
The parameters that we choose to pass to the script will be a separate issue.
My vote is qemu-ifup tapname macaddr (with macaddr being what was specified
on the -net command line or the appropriate default).
Ok.
The fact that we don't know what Fabrice think about this subjet is a
problem. Only Fabrice can commit to the qemu CVS as I understand. I hope
Fabrice read this list and can provids to us usefull informations on how
to make the patch to get it accepted.
Actually a lot of the issues have been discussed before. The -net syntax was
his idea I believe. Once Fabrice makes his opinion known, he generally will
keep quiet until code appears.
Once the patch is written, then we can start asking Fabrice for changes or
improvements needed to make the patch commitable (as then we'll actually have
something substantial for him to look at).
Ok. I havn't read all the posts into this maling list, but I hope the
indications you provids are the conclusion of what has been discussed
before.
--
Jean-Christian de Rivaz
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Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Sun, 2 Oct 2005, Jean-Christian de Rivaz wrote: It's already the case with at least my proposed patch. I have't tested the patch written by Henrik Nordstrom or Lars Munch but it's likly that there work the same way since this feature come from the Linux kernel tun code. Indeed. It is impossible to support persistent TUN/TAP devices without not also supporting dynamically created devices. In fact, if qemu supported both these things, then I don't see a reason for -tun-fd at all (except for something like VDE). Agree, and a -vde option will go forward in this direction. vde is not the only userspace switch available. Locking qemu to only vde would be bad. I then much prefer not having the builtin vde option or even the tun/tap open code and only keep -tun-fd. (from -tun-fd all the others can be implemented by a wrapper opening the connections and handing them over to QEMU) So an open question: is the -tun and -vde options a good idea to cleanup the network interface options? No. To be clear, I don't propose to remove option at this point, but just to make qemu more easy to use for simple and most common setup. See the proposal from Fabrice some month ago on what the command line parameters should look like. Very nice imho. And very easy to extend with new modes (VDE, persistent TUN/TAP, whatever) without having to introduce new confusing options. Regards Henrik ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
Henrik Nordstrom a écrit : On Mon, 3 Oct 2005, Jean-Christian de Rivaz wrote: The idea of the -vde option is to have in parameter the VDE socket (default to /tmp/vde.ctl) an act like vde_plug so it don't need any other code to work. Just start a vde_switch and as many qemu -vde you wants to create a complete virtual nework (1 switch and n hosts). Or in line with the earlier proposal of a -net option: -net vde,socket=/path/to/vde.ctl,group=xxx where socket defaults to /tmp/vde.ctl and group defaults to 0 if not specified. Nice. I think that a syntax like -net type[:macaddr][,arg[,arg[...]]] is more usefull, since the MAC addresse of the TAP devices is not alway specified as it can be set randomly by the Linux kernel (with possible collision see code in include/linux/etherdevice.h). The MAC of the TUN/TAP device on the host side is a completely different thing and is the MAC the HOST should use on that virtual ethernet. What the option to QEMU specifies is the MAC QEMU should use. Ok. I was wrong sorry. In case of this new interface, will network script still needed. If yes, how should we handle them in the new option syntax ? -net ...,script=/path/to/script Ok, can't be more clean. -- Jean-Christian de Rivaz ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
Henrik Nordstrom a écrit : On Sun, 2 Oct 2005, Jean-Christian de Rivaz wrote: It's already the case with at least my proposed patch. I have't tested the patch written by Henrik Nordstrom or Lars Munch but it's likly that there work the same way since this feature come from the Linux kernel tun code. Indeed. It is impossible to support persistent TUN/TAP devices without not also supporting dynamically created devices. Agree. My patch don't drop the dynamic way to use TUN/TAP! Or it has a bug in it. vde is not the only userspace switch available. Locking qemu to only vde would be bad. I then much prefer not having the builtin vde option or even the tun/tap open code and only keep -tun-fd. (from -tun-fd all the others can be implemented by a wrapper opening the connections and handing them over to QEMU) I don't want to stop support of others virtual switch or whatever new interfaces! I just tell about VDE because I like it. Now ok, you can arg that you can make everything with a -tun-fd option, but this requier a wrapper for every use and this is I think the best way to confuse users. See the proposal from Fabrice some month ago on what the command line parameters should look like. Very nice imho. And very easy to extend with new modes (VDE, persistent TUN/TAP, whatever) without having to introduce new confusing options. Ok. -- Jean-Christian de Rivaz ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Mon, Oct 03, 2005 at 03:07:02PM +0200, Henrik Nordstrom wrote: On Sun, 2 Oct 2005, Jim C. Brown wrote: Only objection is that for the tunfd case I would use -net tap,fd=10,macaddr=... Since it doesn't have to be a tap device, how about this? -net socket,fd=10,macaddr=... For the tap type we could have a 3rd optional parameter for the name, e.g. -net tap,macaddr,name (with name defaulting to tapX if its not specified). What about this: -net tap,ifname=qemu0,macaddr=... That looks fine. Regards Henrik -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Mon, Oct 03, 2005 at 03:01:08PM +0200, Henrik Nordstrom wrote: On Sun, 2 Oct 2005, Jean-Christian de Rivaz wrote: In fact, if qemu supported both these things, then I don't see a reason for -tun-fd at all (except for something like VDE). Agree, and a -vde option will go forward in this direction. vde is not the only userspace switch available. Locking qemu to only vde would be bad. I then much prefer not having the builtin vde option or even the tun/tap open code and only keep -tun-fd. (from -tun-fd all the others can be implemented by a wrapper opening the connections and handing them over to QEMU) Agreed. So -net socket,fd=... or at least -socket-fd (I think it should be made clear that qemu won't require tap fds, just datagram sockets.) To be clear, I don't propose to remove option at this point, but just to make qemu more easy to use for simple and most common setup. See the proposal from Fabrice some month ago on what the command line parameters should look like. Very nice imho. And very easy to extend with new modes (VDE, persistent TUN/TAP, whatever) without having to introduce new confusing options. Agreed. Regards Henrik ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Mon, Oct 03, 2005 at 02:54:42PM +0200, Henrik Nordstrom wrote: On Sun, 2 Oct 2005, Jim C. Brown wrote: What it really boils down to is cleaning up the command line options for the network interface(s), which up to now have been added in a hackish, piece-wise manner. And persistent TUN TAP devices makes it extremely clean on the host, and as it is not difficult for qemu there is not really any reason why not. One could obviously drop all the TUN/TAP setup code from qemu, requiring the user to wrap qemu in some application passing it already opened sockets using -tun-fd, but this will be a bit cumbersome to users.. but on the other hand not worse than the users using VDE or similar userspace switches/hubs. This is definitely the wrong way to go. A separate program shouldn't be necessary for handling what is probably the most common networking mode for qemu. qemu should support using tap devices (persistent or otherwise) on its own in an easy-to-understand manner. In fact, I like Fabrice's -net syntax. An argument for adding vde support in qemu itself does exist - but VDE provides its own wrapper so thats not really too much hassle for the end user. Also, VDE may not be popular enough to justify adding vde-specific code to qemu. (I haven't taken any polls, so I don't know if it is or not. Personally I would have no objection. BTW, it seems bochs has native support for vde now.) In fact, if qemu supported both these things, then I don't see a reason for -tun-fd at all (except for something like VDE). VDE and a number of other similar applications is a fairly strong reason to support the -tun-fd functionality I would say. I'd argue that -tun-fd is the wrong name. However, there may be less popular switches (maybe someone can make qemu run on uml_switch for example) - so the functionality should stay. Incidently, does the current -tun-fd code work for windows hosts? Regards Henrik ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
Hi, Sorry for the lack of comment. I mostly use the 'user-net' networking so I never bothered much about TUN/TAP. What I can say is that the '-net xxx' option will be implemented to solve the existing issues. My only concern is about ensuring backward compatibility (if no one needs it then it is much simpler). Another point is that I am very tempted to integrate a feature to connect several qemu without needing an external program such as VDE. I am thinking of it because it would be relatively easy to add to the existing user-net code (user-net already simulates a kind of LAN). Fabrice. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
Christian MICHON a écrit : to do so, does that mean we would need to launch a 1st qemu instance which would contain the dhcp server, and next qemu instances would connect to it ? if so, 'qemu -server' and 'qemu -client -connect_to server' could be useful... As I understand and with what I know, you can do that now using a virtual network (VDE for example). What matter is that fact that two qemu instances are connected on the same network. DHCP protocol (like any others netowrk protocol) is over that network and is not visible to qemu. To do what you wants, you have to use to different operating system image, one that contains a DHCP server, and the second that contain a DHCP client. 1) create a virtual switch: vde_switch -s /tmp/my_switch.ctl 2) start a virtual server: vdeq -s /tmp/my_switch.ctl qemu-softmmu -hda dhcp-server.bin [...] 3) start a virtual client: vdeq -s /tmp/my_switch.ctl qemu-softmmu -hda dhcp-client.bin [...] -- Jean-Christian de Rivaz ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Mon, Oct 03, 2005 at 08:29:13PM +0200, Fabrice Bellard wrote: Hi, Sorry for the lack of comment. I mostly use the 'user-net' networking so I never bothered much about TUN/TAP. What I can say is that the '-net xxx' option will be implemented to solve the existing issues. My only concern is about ensuring backward compatibility (if no one needs it then it is much simpler). Doubtful. Not many use tundev.c or tapdev.c VDE is more popular but fixing it for a new syntax is a trivial change. (Probably a one liner, even.) AFAIK nothing else will care. Another point is that I am very tempted to integrate a feature to connect several qemu without needing an external program such as VDE. I am thinking of it because it would be relatively easy to add to the existing user-net code (user-net already simulates a kind of LAN). How would the syntax for this work? Fabrice. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Sun, 2 Oct 2005, Jean-Christian de Rivaz wrote: Yes. This is just an update of my first patch posted the 13 january 2005 so it should apply without offset warning. Maybe can I propose to joint our effort ? What remains to make it complete is the command line parser, allowing network options to be specified in a reasonable manner. See discussions some time ago regarding MAC addresses. Regards Henrik ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Sun, Oct 02, 2005 at 12:24:53PM +0200, Henrik Nordstrom wrote: On Sun, 2 Oct 2005, Jean-Christian de Rivaz wrote: Yes. This is just an update of my first patch posted the 13 january 2005 so it should apply without offset warning. Maybe can I propose to joint our effort ? What remains to make it complete is the command line parser, allowing network options to be specified in a reasonable manner. See discussions some time ago regarding MAC addresses. Regards Henrik The use existing tun/tap network interface is is a popular patch to create. I also did one in november 2004 :-) http://lists.gnu.org/archive/html/qemu-devel/2004-11/msg00454.html -- Lars Munch ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking: patch for existing tun
On Sun, Oct 02, 2005 at 01:45:16PM -0500, Anthony Liguori wrote: I don't understand, why is this patch needed? It makes qemu easier to use. A lot easier to use a persistent tap by doing qemu -use-already-open-tap tap1 instead of hacking around with persistenttapdev.c It's a pretty simple C program to create a tun device by whatever name you want and just pass the fd to qemu via -tun-fd. I think it's generally better to have the least number of options necessary to make things easier to understand. Like the way vdeq/vdeqemu does it? That works, but is that really the best way to handle it? vdeq works the way it does because the odds of getting a special -vde-socket option in qemu were moot. And perhaps so the author of VDE could have control over what options vdeq supported. (In the case of vdeq, its a clever hack: both tuntap devices and sockets are controlled via fds, so vdeq sends a socket fd instead of a tuntap fd and qemu is none the wiser. Hypothetically one could even pass a regular file via -tun-fd.) Having an option for specifying tuntap devices by name on the command line (persistent or not) is the cleanest way to do it, and also the easiest for the user. Maybe even make it so we just pass an option -tap tap0: if tap0 doesnt exist then qemu creates a new device with that name, if it does exist then qemu opens it as if it were a persistent tuntap. In fact, if qemu supported both these things, then I don't see a reason for -tun-fd at all (except for something like VDE). Is it really something that so many people would want to use that it warrants making it an option? Is there a concrete use-case that this enables? What it really boils down to is cleaning up the command line options for the network interface(s), which up to now have been added in a hackish, piece-wise manner. Regards, Anthony Liguori Maybe can I propose to joint our effort ? ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Jim C. Brown schrieb: On Fri, Sep 30, 2005 at 03:13:21PM -0700, Don Kitchen wrote: [...] I'm interested in the handling of ethernet frames because I haven't been able to get the bridge to pass packets between added interfaces (yes, they're all up and promisc) and I'm not too thrilled with networking being bridged anyway, Do you mean the kernel bridge, br0? Or are you talking about some sort of user space bridge, like bridged (which uses a series of packet sockets to bridge between multiple ethernet (ethX) devices) ? and it seems to me that if an fd were hooked up to a BPF capturing everything from the real ethernet device in promiscuous mode, and pushing out any raw frames it receives, that I could bypass the bridge and make it as if the emulator's virtual ethernet device is a real one. Or is there some reason this won't work? (after all, other products don't have this, there must be a reason right?) Ah, you're talking about using a packet socket, right? That works fine for the most part. There is one thing that you have missed though: guest-host communication doesn't work when you do that. When you push out a raw frame, it leaves the real ethernet device before the host sees it. So guest-host doesn't work. You need to find another way to send packets from the guest to the host. Most host OSes will not let you do this at all. (Windows seems to be the exception, winpcap's pcap_sendpacket() appears to work fine for that job.) That means it would work if the host NIC is connected to a switch? Then the switch would send packets from the guest which are meant for the host back to the host NIC and everything's fine! Or did I misunderstand that now? Regards, Oliver Gerlich -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFDPnM2TFOM6DcNJ6cRAlTaAJ9gxN9CUnSEeKl5lPbURTEh33Rl8QCgpmNV cUuiGGOkpPVYxzeo9ZoksWM= =tEkV -END PGP SIGNATURE- ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking
On Sat, Oct 01, 2005 at 10:12:41AM +0200, Jean-Christian de Rivaz wrote: Jim C. Brown a ?crit : Typically, tapX (tap0, tap1, etc) names are reserved for tap devices (ethernet frames) and tunX (tun0, tun1, etc) are reserved for tun devices (IP frames). qemu breaks those rules and calls the tap device that it creates tun0. This is done for reasons that Fabrice has not made clear. (I assume there is a reason for it because he has refused to apply any of the patches that fix this.) You point the real question: why it has been impossible to get accepted any patch that fixed this. I has proposed one myself and I get no comment at all. I see similar effort from others and obviousely there failed almost the same way. No getting any valuable comment about why a idea proposed by many peopoles is not applyed make this subject very hard. The change I was talking about is a one line patch... It's annoying that Fabrice has said nothing about it. But it doesn't actually mess anything up, it's just confusing for advanced users. I presume that the device qemu makes is called tun0 because Fabrice wants to make clear that he doesnt use (and wont support) the ethertap device. Not a very good reason. (Or maybe he wants to keep it tun0 because if he changed the name he'd have to change the option -tun-fd to -tap-fd and that'd break some scripts.) I hope that we can resolve this subject, because in my point of view, using a existing tun is far more simpler than create one the way quemu do; I never mentioned that. At all. And qemu already supports that, via the -tun-fd option. and this open a lot of new uses in terme of the network managment of the quemu instance. The very first one for me is to allow only root to setup a DHCP server and to assign tuns interfaces to the users that needs it, so there don't even have to think about the network setup, ther just boot into quemu an OS with a DHCP client. That is a little tricky to do - but qemu can do it. Any comment this time ? -- Jean-Christian de Rivaz ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking
On Saturday 01 October 2005 14:07, Jim C. Brown wrote: On Sat, Oct 01, 2005 at 01:30:06PM +0200, Oliver Gerlich wrote: That means it would work if the host NIC is connected to a switch? Then the switch would send packets from the guest which are meant for the host back to the host NIC and everything's fine! Or did I misunderstand that now? If the switch sends packets from the host NIC back to itself, I believe that would work. A switch will not send a packet back where it came from. That would be a sure way to introduce infinite forwarding loops. Paul ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking
On Sat, 1 Oct 2005, Oliver Gerlich wrote: That means it would work if the host NIC is connected to a switch? Then the switch would send packets from the guest which are meant for the host back to the host NIC and everything's fine! Or did I misunderstand that now? In this kind of setup you will need two NICs in the host for this to work. One NIC used by the guest, the other by the host. If you have more than one guest and wants the guests to be able to talk to each other then you basically need one NIC per guest. Just being connected to a switch does not help as switched (and even hubs) does not bounce packets back on the same port they came from. Regards Henrik ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking
Henrik Nordstrom a écrit : On Sat, 1 Oct 2005, Jean-Christian de Rivaz wrote: You point the real question: why it has been impossible to get accepted any patch that fixed this. I has proposed one myself and I get no comment at all. I see similar effort from others and obviousely there failed almost the same way. No getting any valuable comment about why a idea proposed by many peopoles is not applyed make this subject very hard. I think it is in part due to the command line parsing of network parameters being all crap and need to be replaced by something more sane. Ok. So if the command line parsing of network parameters is crap for someone, he is free to improve it. But, sorry, I found that not a valid excuse to silently reject others featurs to the network setup. I will be very happy to modify the patch I propose to be compliant with a new network parameters parsing code. I hope that we can resolve this subject, because in my point of view, using a existing tun is far more simpler than create one the way quemu do I agree that persistent tun tap devices is much easier to work with. Thanks. :-) -- Jean-Christian de Rivaz ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking
On Sat, Oct 01, 2005 at 10:24:03PM +0200, Jean-Christian de Rivaz wrote: And qemu already supports that, via the -tun-fd option. Can you please give me an exemple how to use the -tun-fd option to open an existing tun (i.e: tun-alice) ? This option only work for already opened tap/tun interface as I understand. I see what you mean now. qemu itself has no direct support for persistent tuntap devices. However, I imagine that one could modify tundev.c or tapdev.c to open a persistent tuntap device (by name) and then pass the fd to qemu via -tun-fd. It would be better if qemu had direct support for them of course. -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking
Jim C. Brown a écrit : On Sat, Oct 01, 2005 at 10:24:03PM +0200, Jean-Christian de Rivaz wrote: And qemu already supports that, via the -tun-fd option. Can you please give me an exemple how to use the -tun-fd option to open an existing tun (i.e: tun-alice) ? This option only work for already opened tap/tun interface as I understand. I see what you mean now. qemu itself has no direct support for persistent tuntap devices. However, I imagine that one could modify tundev.c or tapdev.c to open a persistent tuntap device (by name) and then pass the fd to qemu via -tun-fd. It would be better if qemu had direct support for them of course. Where are this tundev.c or tapdev.c files ? I just updated qemu from CVS and I found no files named like this. [EMAIL PROTECTED]:~/qemu/qemu$ cvs -qz9 update -AdP ? tun2.patch M qemu-doc.texi M vl.c [EMAIL PROTECTED]:~/qemu/qemu$ find . -type f -name t*dev* [EMAIL PROTECTED]:~/qemu/qemu$ -- Jean-Christian de Rivaz ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking
I have some questions about the networking that I hope someone can answer. Qemu is able to use tun tap devices. I've taken the tundev.c program, which opens a tun device and passes the fd to qemu, and compared it to the tapdev.c program (which qemu is also able to use) and there's very little difference to how it's opened. According to the little tun/tap documentation I understand, the tap descriptor should be providing ethernet frames instead of the IP packets [ethernet payloads] that tun should be providing. But qemu does not seem to differentiate between the two types of file descriptors passed by tundev and tapdev respectively, so I am a little confused how qemu can work with both types of fd's. Qemu only uses tap devices (ie. ethernet frames). I'm interested in the handling of ethernet frames because I haven't been able to get the bridge to pass packets between added interfaces (yes, they're all up and promisc) and I'm not too thrilled with networking being bridged anyway, and it seems to me that if an fd were hooked up to a BPF capturing everything from the real ethernet device in promiscuous mode, and pushing out any raw frames it receives, that I could bypass the bridge and make it as if the emulator's virtual ethernet device is a real one. Or is there some reason this won't work? (after all, other products don't have this, there must be a reason right?) The host doesn't see the packets set with BFP. Paul ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
Re: [Qemu-devel] tun/tap networking
On Fri, Sep 30, 2005 at 03:13:21PM -0700, Don Kitchen wrote: I've used that one pricey product at work, but it always seemed a bit expensive for home users. But I only knew about some of the other emulators, the ones that are so slow you wonder why didn't they warn you not to bother downloading the thing to start with. But qemu has definately made it past usability barrier. Because qemu is not an emulator per se, it is properly called a dynamic translator. (It's a distinction that many will quarrel over for a long time. ;) I have some questions about the networking that I hope someone can answer. Qemu is able to use tun tap devices. I've taken the tundev.c program, which opens a tun device and passes the fd to qemu, and compared it to the tapdev.c program (which qemu is also able to use) and there's very little difference to how it's opened. According to the little tun/tap documentation I understand, the tap descriptor should be providing ethernet frames instead of the IP packets [ethernet payloads] that tun should be providing. But qemu does not seem to differentiate between the two types of file descriptors passed by tundev and tapdev respectively, so I am a little confused how qemu can work with both types of fd's. I am confused as well. Are you sure that tundev.c creates a tun device? Or is it creating a tap device that is named tun0? Typically, tapX (tap0, tap1, etc) names are reserved for tap devices (ethernet frames) and tunX (tun0, tun1, etc) are reserved for tun devices (IP frames). qemu breaks those rules and calls the tap device that it creates tun0. This is done for reasons that Fabrice has not made clear. (I assume there is a reason for it because he has refused to apply any of the patches that fix this.) qemu has no support for true tun devices. It only deals with ethernet frames, so it only works with tap devices. You can tell because a tap device is opened when you add a special flag, IFF_TAP, to the ifr_flags of the TUNSETIFF ioctl call. I'm interested in the handling of ethernet frames because I haven't been able to get the bridge to pass packets between added interfaces (yes, they're all up and promisc) and I'm not too thrilled with networking being bridged anyway, Do you mean the kernel bridge, br0? Or are you talking about some sort of user space bridge, like bridged (which uses a series of packet sockets to bridge between multiple ethernet (ethX) devices) ? and it seems to me that if an fd were hooked up to a BPF capturing everything from the real ethernet device in promiscuous mode, and pushing out any raw frames it receives, that I could bypass the bridge and make it as if the emulator's virtual ethernet device is a real one. Or is there some reason this won't work? (after all, other products don't have this, there must be a reason right?) Ah, you're talking about using a packet socket, right? That works fine for the most part. There is one thing that you have missed though: guest-host communication doesn't work when you do that. When you push out a raw frame, it leaves the real ethernet device before the host sees it. So guest-host doesn't work. You need to find another way to send packets from the guest to the host. Most host OSes will not let you do this at all. (Windows seems to be the exception, winpcap's pcap_sendpacket() appears to work fine for that job.) VMware gets around this by using its kernel module: when the guest sends something to the host, VMware passes the packet to its kernel module, which injects it into the incoming packet stream. Without your own kernel module though, you can't do this. Thanks ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel -- Infinite complexity begets infinite beauty. Infinite precision begets infinite perfection. ___ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
