Re: [Xen-users] PV DomU kernel 2.4(.34) for IPCop

[Paul Schulze <avlex@xxxxxxx>]

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Hi Mark,

> > I am currently in the process of setting up a firewall/access point
> > DomU and I would like to know if there is any way to run a linux
> > kernel 2.4(.34) based system as a DomU. The primary reason for this
> > is that I want to run IPCop on such a kernel, but also that I
> > consider kernel 2.4 based systems to be more suitable for some
> > applications, especially for use as a firewall.
> I've seen some patches for 2.4 PV-on-HVM drivers support - and I  
> *think* I've
> seen patches for 2.4 domU support floating around.  However, you  
> need more
> than this because you're looking at PCI passthrough.  Doing PCI  
> passthrough
> to a domU requires more than just Xen domU support in that kernel,  
> since it
> also needs to talk to real hardware.  I'm not aware of patches  
> allowing this
> under Linux 2.4, although Linux 2.6 is well supported in this regard.
>
> PCI passthrough to an HVM domain wouldn't have this limitation but  
> would, as
> you observe, require VT-d support currently :-(
If you could point me to the patches you mentioned, I would be  
grateful, since I myself couldn't turn up anything of the sort in the  
last few days. I am aware of the fact, that I would need patches that  
add most of the Xen support in kernel 2.6 to kernel 2.4, including  
the PCI frontend module. I will worry about that as soon as I have at  
least something to work with. I'm not worried about my NICs though,  
they should be well supported by kernel version 2.4.34 to 36 and  
those are the versions I am currently aiming for.

> > P.S.: I know, this setup sounds kind of paranoid, isolating Dom0 that
> > much and I might hit a wall somewhere because certain things are not
> > possible yet (thats actually one of the points of this experiment, to
> > see what Xen can do). I also realize it is pointless unless I use a
> > system with IOMMU in a PCI passthrough setup (ultimately enabling PCI
> > Passthrough to HVM), but for me it is more like a proof of concept,
> > than a security concern for the machine in question and I prefer to
> > run Linux on Xen paravirtualized anyway. If anyone has some thoughts
> > on this, he or she would like to share, I am always thankful for
> > advise or another point of view.
> Are you aware that there have been patches posted (and possibly  
> merged now, I
> think, although not in a release) that support IOMMU protection for  
> PCI
> passthrough to PV domUs?  This would be useful for the kind of  
> setup you
> propose, should you wish to avoid the overheads of HVM.
I was not aware of that, but what I meant is, if I had hardware IOMMU  
support, I would not have to worry about running kernel 2.4. The  
overhead of running the system in a HVM isn't all that important at  
the moment, considering Xen seems to have problems with AMD's  
Cool&Quiet on my system anyways (so I do have quiet a bit of CPU time  
to spare).
Thanks,


Paul.

- --
Paul Schulze
avlex@xxxxxxx
Public Key: http://solaris-net.dyndns.org/keys/key_avlex.asc

"Making mistakes is human,
but to really fuck things up you need Computers"

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