Re: [PATCH v2 01/29] hw/core: Allow setting 'virtio-blk-device.scsi' property on OSX host

[Cornelia Huck]

On Wed, 29 Jan 2020 22:23:17 +0100
Philippe Mathieu-Daudé <address@hidden> wrote:

> Commit ed65fd1a27 restricted the 'scsi' property to Linux hosts:

It was restricted to Linux hosts before that commit; that only became
problematic because we set it unconditionally in the compat code.

> 
>   1261 static Property virtio_blk_properties[] = {
>   1262     DEFINE_BLOCK_PROPERTIES(VirtIOBlock, conf.conf),
>   ...
>   1268 #ifdef __linux__
>   1269     DEFINE_PROP_BIT64("scsi", VirtIOBlock, host_features,
>   1270                       VIRTIO_BLK_F_SCSI, false),
>   1271 #endif

What about:

Commit ed65fd1a2750 ("virtio-blk: switch off scsi-passthrough by
default") changed the default value of the 'scsi' property of
virtio-blk, which is only available on Linux hosts. It also added an
unconditional compat entry for 2.4 or earlier machines.

> 
> When we try to set this property on a pre-2.4 machine on OSX,

Pre-2.5, I think?

> we get:
> 
>    Unexpected error in object_property_find() at qom/object.c:1201:
>    qemu-system-x86_64: -device virtio-blk-pci,id=scsi0,drive=drive0: can't 
> apply global virtio-blk-device.scsi=true: Property '.scsi' not found
> 
> Fix this error by marking the property optional.
> 
> Fixes: ed65fd1a27

Fixes: ed65fd1a2750 ("virtio-blk: switch off scsi-passthrough by default")

> Suggested-by: Cornelia Huck <address@hidden>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
>  hw/core/machine.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 3e288bfceb..d8e30e4895 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -148,7 +148,8 @@ GlobalProperty hw_compat_2_5[] = {
>  const size_t hw_compat_2_5_len = G_N_ELEMENTS(hw_compat_2_5);
>  
>  GlobalProperty hw_compat_2_4[] = {
> -    { "virtio-blk-device", "scsi", "true" },
> +    /* Optional because the 'scsi' property is Linux-only */
> +    { "virtio-blk-device", "scsi", "true", .optional = true },
>      { "e1000", "extra_mac_registers", "off" },
>      { "virtio-pci", "x-disable-pcie", "on" },
>      { "virtio-pci", "migrate-extra", "off" },

Reviewed-by: Cornelia Huck <address@hidden>