Re: [PATCH 05/10] xen/arm: vgic-v3: Document the current restrictions

[Ian Campbell <Ian.Campbell@citrix.com>]

On Mon, 2015-01-19 at 16:29 +0000, Julien Grall wrote:
> The current vGIC v3 driver doesn't fully implement GICv3 spec:
>     - GICv3 backward compatibility is not supported (GICD_CTLR.ARE = 0)

I think you meant GICv2 here as you did in the code.

In which case I believe this is optional in the spec, i.e. we can be
compliant and still not implement this.

That's not to say it isn't desirable, but this is a TODO item, not a
spec non-conformity issue.

>     - A processor can only access his own redistributor. For buggy
>     assumption, the current code bank the redistributors MMIO.

What assumption? It's not clear if you mean that a foreign redistributor
should not be accessible and is, or if it should be accessible and
isn't.

> 
> Signed-off-by: Julien Grall <julien.grall@linaro.org>
> ---
>  xen/arch/arm/vgic-v3.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
> index 1fa1413..9818a6b 100644
> --- a/xen/arch/arm/vgic-v3.c
> +++ b/xen/arch/arm/vgic-v3.c
> @@ -16,6 +16,11 @@
>   * but WITHOUT ANY WARRANTY; without even the implied warranty of
>   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>   * GNU General Public License for more details.
> + *
> + * Current limitation of the vGIC v3:
> + *      - GICv2 backward compatibility is not supported (GICD_CTRL.ARE = 0)
> + *      - A processor can only access his own redistributor. For buggy
> + *      assumption, the current code bank the redistributors MMIO
>   */
>  
>  #include <xen/bitops.h>