[vfio-users] IOMMU group is not a symlink - SR-IOV on 32Bit MMIO platform?

[Taiidan at gmx.com]

error: internal error: Process exited prior to exec: libvirt:  error : 
internal error: Invalid device 0000:09:00.1 iommu_group file 
/sys/bus/pci/devices/0000:09:00.1/iommu_group is not a symlink

(intel 82576 quad port nic, assigning itself works fine)

I am trying to get sr-iov working on a platform with 32bit MMIO space 
(is that even possible)

So I have added pci-realloc and pci-assign-buses to the kernel command 
line, without that I get a "Not enough MMIO resources for SR-IOV" error 
even when adding just one VF via sysfs.

I also get an error about not enough space for BAR's in dmesg with or 
without the cmdline additions but with the cmdline parms the vf bars 
seem to allocate fine.

[    2.705747] pci 0000:07:00.0: VF(n) BAR0 space: [mem 
0x00000000-0x0001ffff 64bit] (contains BAR0 for 8 VFs)
[    2.715887] pci 0000:07:00.0: VF(n) BAR3 space: [mem 
0x00000000-0x0001ffff 64bit] (contains BAR3 for 8 VFs)
[    2.726342] pci 0000:07:00.1: VF(n) BAR0 space: [mem 
0x00000000-0x0001ffff 64bit] (contains BAR0 for 8 VFs)
[    2.736477] pci 0000:07:00.1: VF(n) BAR3 space: [mem 
0x00000000-0x0001ffff 64bit] (contains BAR3 for 8 VFs)
[    2.763896] pci 0000:09:00.0: VF(n) BAR0 space: [mem 
0x00000000-0x0001ffff 64bit] (contains BAR0 for 8 VFs)
[    2.774036] pci 0000:09:00.0: VF(n) BAR3 space: [mem 
0x00000000-0x0001ffff 64bit] (contains BAR3 for 8 VFs)
[    2.784487] pci 0000:09:00.1: VF(n) BAR0 space: [mem 
0x00000000-0x0001ffff 64bit] (contains BAR0 for 8 VFs)
[    2.794621] pci 0000:09:00.1: VF(n) BAR3 space: [mem 
0x00000000-0x0001ffff 64bit] (contains BAR3 for 8 VFs)

I get this message and see the VF's in lspci but there isn't any IOMMU 
group allocated.
[  116.175246] igb 0000:07:00.0: 1 VFs allocated
[  420.514477] igb 0000:09:00.1: 1 VFs allocated

Would disabling devices in the BIOS help?