On Wed, Apr 22, 2009 at 12:50:00PM +1000, Simon Horman wrote:
> I've poked a little further into this and the problem is partly
> a missunderstanding on my part.
> In the case where a function is specified in the hvm.conf in
> the form BUS:DEV:FUNC (e.g. 00:1d.0), then there is a check inside
> xm that prevents the function from subsequently being hot-unplugged.
> The check is that the vslot number is set to auto-select. And presumably
> the idea was that statically assigned devices couldn't be hot-unplugged,
> which to be honest was my initial assumption of how things work.
> If, however, the function in the hvm.conf is of the form BUS:DEV:FUNC@VSLOT
> (e.g. 00:1d.00@1e) which I added recently, then the check is bypassed,
> because vslot is set to 1e not auto. This is how I was doing my tests. I
> assumed this was the behaviour for all cases, and documented it as such.
> This leaves us with 3 choices:
> 1. Leave the inconsistency, which seems like a bad idea.
> 2. Add a check to make sure both forms can't be hot-unplugged
> This is more work than;
> 3. Remove the check and allow statically assigned devies to be removed.
> This seems like a good option, and if there is consensus I can
> fix this up into a propper patch.
> diff -r 6ba4e34d21d3 tools/python/xen/xend/XendDomainInfo.py
> --- a/tools/python/xen/xend/XendDomainInfo.py Tue Apr 21 16:31:26 2009 +0100
> +++ b/tools/python/xen/xend/XendDomainInfo.py Wed Apr 22 12:42:58 2009 +1000
> @@ -1092,9 +1092,6 @@
> if devnum >= pci_len:
> raise VmError("Device @ vslot 0x%x doesn't exist." % (vslot))
> - if vslot == AUTO_PHP_SLOT:
> - raise VmError("Device @ vslot 0x%x doesn't support hotplug." %
> # Check the co-assignment.
> # To pci-detach a device D from domN, we should ensure: for each DD
> in the
> # list of D's co-assignment devices, DD is not assigned (to domN).
I now believe the analysis above to be incorrect and the patch provided
not to be apropriate for 3.4.
I have posted a new fix to xen-devel as "xm: Fix hot-unplug of
VA Linux Systems Japan K.K. Satellite Lab in Sydney, Australia
H: www.vergenet.net/~horms/ W: www.valinux.co.jp/en
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