Hi Jean-Philippe,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.16-rc2 next-20180221]
[cannot apply to iommu/next]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Jean-Philippe-Brucker/Add-virtio-iommu-driver/20180217-075417
config: arm64-allmodconfig (attached as .config)
compiler: aarch64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=arm64 

All errors (new ones prefixed by >>):

   aarch64-linux-gnu-ld: arch/arm64/kernel/head.o: relocation R_AARCH64_ABS32 against `_kernel_offset_le_lo32' can not be used when making a shared object
   arch/arm64/kernel/head.o: In function `kimage_vaddr':
   (.idmap.text+0x0): dangerous relocation: unsupported relocation
   arch/arm64/kernel/head.o: In function `__primary_switch':
   (.idmap.text+0x340): dangerous relocation: unsupported relocation
   (.idmap.text+0x348): dangerous relocation: unsupported relocation
   drivers/iommu/virtio-iommu.o: In function `viommu_probe':
   virtio-iommu.c:(.text+0xbdc): undefined reference to `virtio_check_driver_offered_feature'
   virtio-iommu.c:(.text+0xcfc): undefined reference to `virtio_check_driver_offered_feature'
   virtio-iommu.c:(.text+0xe10): undefined reference to `virtio_check_driver_offered_feature'
   drivers/iommu/virtio-iommu.o: In function `viommu_send_reqs_sync':
   virtio-iommu.c:(.text+0x130c): undefined reference to `virtqueue_add_sgs'
   virtio-iommu.c:(.text+0x1398): undefined reference to `virtqueue_kick'
   virtio-iommu.c:(.text+0x14d4): undefined reference to `virtqueue_get_buf'
   drivers/iommu/virtio-iommu.o: In function `virtio_iommu_drv_init':
   virtio-iommu.c:(.init.text+0x1c): undefined reference to `register_virtio_driver'
   drivers/iommu/virtio-iommu.o: In function `virtio_iommu_drv_exit':
>> virtio-iommu.c:(.exit.text+0x14): undefined reference to `unregister_virtio_driver'

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