Re: [Xen-devel] [PATCH V1 18/29] xen/arm: Don't map disabled device in DOM0

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-08-28 at 15:47 +0100, Julien Grall wrote:
> Linux should cope with 'status = "disabled"' in the Device Tree.

This is devices which were disabled in the DT passed to Xen, rather than
ones which we have disabled ourselves (e.g. the previous patch)?

> This solution can be used later to pass-through device to a specific guest.

How? I thought disabled meant "not present/wired-up on this variant of
the platform"? A user cannot be expected to edit the host DTB to enable
passthrough. We might want a dtb_hide cmdline option, or to do it
dynamically like pciback is capable of.

Or maybe I'm wrong above and this is indeed devices we have disabled
ourselves?

> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> 
> ---
>     Changes in v2:
>         - Add a comment
> ---
>  xen/arch/arm/domain_build.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index d56bc70a..11f247b 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -416,9 +416,13 @@ static int handle_node(struct domain *d, struct 
> kernel_info *kinfo,
>       *  - Device used by Xen: Obviously dom0 can't use them
>       *  - Memory: the guest will see a different view of memory. It will
>       *  be allocated later.
> +     *  - Disabled device: Linux is able to cope with status="disabled"
> +     *  property. Therefore these device doesn't need to be mapped. This
> +     *  solution can be use later for pass through.
>       */
>      if ( dt_device_used_by(np) != DOMID_XEN &&
> -         !dt_device_type_is_equal(np, "memory") )
> +         !dt_device_type_is_equal(np, "memory") &&
> +         dt_device_is_available(np) )
>      {
>          res = map_device(d, np);
>  



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