Re: [Xen-devel] [RFC for-4.5 12/12] drivers/passthrough: arm: Add support for SMMU drivers

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-02-19 at 17:21 +0000, Julien Grall wrote:
> > 
> >> + * This driver currently supports:
> >> + *  - SMMUv1 and v2 implementations (didn't try v2 SMMU)
> > 
> > I guess this is Will's original comment, I thought SMMU-400, which
> > you've tried, was v2?
> 
> No it's SMMU v2. As I understand:
>       - SMMU-400 => SMMU v1
>         - SMMU-500 => SMMU v2

Ah yes, that sounds more familiar.

> The words in parenthesis was added by me because I don't have a test box
> with SMMU v2.

OK.

> >> +#define SZ_4K                               (1 << 12)
> >> +#define SZ_64K                              (1 << 16)
> >> +
> >> +/* Driver options */
> >> +#define SMMU_OPT_SECURE_CONFIG_ACCESS   (1 << 0)
> > 
> > Is this just retained to reduce the deviation from the Linux driver?
> > It's no use to us I think. (I suppose that goes for a bunch of other
> > stuff, eg.. the PGSZ_4K stuff, which I will avoid commenting on
> > further).
> 
> SZ_4K and SZ_64K is used later in the code.

But they are actually useless to us aren't they?

>  The
> SMMU_OPT_SECURE_CONFIG_ACCESS is used for midway as the SMMU is broken.

Ah, so this is effectively a quirk then.

Ian/


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel