Re: [PATCH v3 07/24] vfio/pci: Preserve vfio-pci device files across Live Update

David Matlack
2026-03-24T16:46:39Z

On Tue, Mar 24, 2026 at 6:01 AM Yi Liu <yi.l.liu@intel.com> wrote:
> On 3/24/26 07:57, David Matlack wrote:

> > + * Usage Example
> > + * =============
> > + *
> > + * VFIO PCI devices can be preserved across a kexec by preserving the file
> > + * associated with the device in a LUO session::
> > + *
> > + * device_fd = open("/dev/vfio/devices/X");
>
> /dev/vfio/devices/vfioX

Will fix in v4.

> > + * * The device file must have been acquired from the VFIO character device,
> > + * not ``VFIO_GROUP_GET_DEVICE_FD``.
>
> how about "The device file descriptor must be obtained by opening the
> VFIO device
> character device (``/dev/vfio/devices/vfioX``), not via
> ``VFIO_GROUP_GET_DEVICE_FD``."?
>
> just be aligned with the below words in vfio.rst.
>
> "Traditionally user acquires a device fd via VFIO_GROUP_GET_DEVICE_FD
> user can now acquire a device fd by directly opening a character device
> /dev/vfio/devices/vfioX"

Thanks for the suggestion. Here is the wording I have for v4:

* * The device file being preserved must have been obtained by
opening the
* VFIO character device (``/dev/vfio/devices/vfioX``), not via
* ``VFIO_GROUP_GET_DEVICE_FD``.

> > +#include <linux/kexec_handover.h>
> > #include <linux/kho/abi/vfio_pci.h>
> > #include <linux/liveupdate.h>
> > #include <linux/errno.h>
> > +#include <linux/vfio.h>
>
> maybe follow alphabet order. errno.h would be moved to the top first.

I will reorder errno.h to be at the top in the previous patch (where
the alphabetical ordering issue is introduced).