Re: [Qemu-devel] [PATCH] vfio: allow to disable MMAP per device with -x-mmap=off option

[Eric Blake <eblake@redhat.com>]

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On 02/24/2015 01:38 PM, Samuel Pitoiset wrote:
> Disabling MMAP support uses the slower read/write accesses but allows to
> trace all MMIO accesses, which is not good for performance, but very
> useful for reverse engineering PCI drivers. This option allows to
> disable MMAP per device without a compile-time change.
> 
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
> ---
>  hw/vfio/common.c              | 2 +-
>  hw/vfio/pci.c                 | 1 +
>  include/hw/vfio/vfio-common.h | 2 +-
>  3 files changed, 3 insertions(+), 2 deletions(-)

> +++ b/hw/vfio/pci.c
> @@ -3456,6 +3456,7 @@ static Property vfio_pci_dev_properties[] = {
>      DEFINE_PROP_BIT("x-vga", VFIOPCIDevice, features,
>                      VFIO_FEATURE_ENABLE_VGA_BIT, false),
>      DEFINE_PROP_INT32("bootindex", VFIOPCIDevice, bootindex, -1),
> +    DEFINE_PROP_BOOL("x-mmap", VFIOPCIDevice, vbasedev.allow_mmap, true),

Naming it 'x-mmap' implies it is experimental and may be removed
someday.  Is there any reason why you are not proposing it as a
permanent knob?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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