On Tue, Jun 10, 2014 at 06:47:20PM +0200, lee wrote:
Konrad Rzeszutek Wilk konrad.wilk@oracle.com writes:
On Tue, Jun 10, 2014 at 04:44:23AM +0200, lee wrote:
Konrad Rzeszutek Wilk konrad.wilk@oracle.com writes:
The device should be visible in the dom0 - even when it is for passthrough.
Why should it be visible when it's hidden?
The 'hide' part is to hide it from the device drivers in the initial domain - dom0. That is so that they will not try to use it - as we plan to pass them to a guest. We need it in the dom0 to do admin type work - FLR it, etc.
With Debian, it's not visible in dom0 when the passthrough works. That's how I found out that it does work to begin with, and it makes sense to me.
That is a surprise. If you do 'lspci' in your dom0 do you see the device (06:00.0)?
What does FLR mean? And how do you do something with a device for which no drivers are loaded? I'd find it rather unusual to have a device without drivers and even be able to use it; such devices usually don't show up.
Function Level Reset.
You pass the device to a guest so it can load the drivers and the initial domain (dom0) won't use it.
But irrespective of that - the steps mentioned there are out of date. The correct option should be 'xen-pciback.hide=(06:00.0) xen-pciback.permissive=1'
That's one of the problems: Xen is very poorly documented.
Any help in improving the documentations would be appreciated. Every month we run 'Documentation days' and any work - either on Wiki, manuals, docs, etc would be quite appreciated.
If I have some time, I might make a writeup about how to set up what I did. But it seems I'm using an outdated version of xen, which is what comes with Debian, so by the time I'd finish the writeup, it would be outdated and contribute to confusion more than do any good.
And considering xen, I don't really know anything. I figured out that passthrough doesn't work out of the box on Debian because the module for the device was loaded from the initrd.img before the xen-pciback module and made a bug report because you're supposed to be able to use files in /etc/modprobe.d which can specify dependencies and when you do that, you can't have that just overridden or there's no point in doing that --- and there doesn't seem to be any other way to specify the order in which modules are loaded, and long ago, Debian came up with a policy that things should work out of the box whenever possible (which they might have forgotten by now ...). So maybe they'll fix this problem.
Anyway, it probably goes for other distributions as well, and a hint in the xen docs probably won't hurt.
Please see http://wiki.xenproject.org/wiki/Xen_Project_Document_Days
I tried to make a request to become a "wiki editor". There might be some places in the docs I might be able to make clearer. I don't know if that was successful, though. It seemed to want to redirect me to some google website ...
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