Re: [PATCH v8 2/5] tools: add routine to get CMT L3 event mask

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

On Wed, 2015-01-28 at 16:04 +0800, Chao Peng wrote:
> This is the tools side wrapper for XEN_SYSCTL_PSR_CMT_get_l3_event_mask
> of XEN_SYSCTL_psr_cmt_op.
> 
> Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> ---
>  tools/libxc/include/xenctrl.h |  1 +
>  tools/libxc/xc_psr.c          | 17 +++++++++++++++++
>  tools/libxl/libxl.h           |  1 +

This needs a LIBXL_HAVE #define in libxl.h to advertise the new
functionality.

> +int xc_psr_cmt_get_l3_event_mask(xc_interface *xch, uint32_t *event_mask);

What are the possible values of the event mask? Is there a guarantee
from somewhere that 32-bits is always sufficient?

How can the libxl caller decode the meaning of the bits since they are
not defined in the libxl.h header?

Perhaps a struct of booleans would be a better interface at the libxl
level?

Or perhaps the interface should be more along the lines of "is psr
feature X available", like libxl_psr_..._feature_enabled(ctx,
SOME_SYMBOL)?

Or perhaps the function to actual access the info should have an
ERROR_PSR_FUNCTION NOT_SUPPORTED return?

Ian.