> -----Original Message-----
> From: Joerg Roedel [mailto:[email protected]]
> Sent: Monday, March 23, 2015 7:58 PM
> To: Wu, Feng
> Cc: [email protected]; [email protected];
> [email protected]; [email protected]
> Subject: Re: [v4 2/8] iommu, x86: Define new irte structure for VT-d
> Posted-Interrupts
>
> Hi Feng,
>
> On Mon, Feb 02, 2015 at 04:06:58PM +0800, Feng Wu wrote:
> > Add a new irte_pi structure for VT-d Posted-Interrupts.
> >
> > Signed-off-by: Feng Wu <[email protected]>
> > Reviewed-by: Jiang Liu <[email protected]>
> > Acked-by: David Woodhouse <[email protected]>
> > ---
> > include/linux/dmar.h | 32 ++++++++++++++++++++++++++++++++
> > 1 files changed, 32 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/linux/dmar.h b/include/linux/dmar.h
> > index 8473756..c7f9cda 100644
> > --- a/include/linux/dmar.h
> > +++ b/include/linux/dmar.h
> > @@ -212,6 +212,38 @@ struct irte {
> > };
> > };
> >
> > +struct irte_pi {
>
> I think it is better to put this as a union into struct irte. It saves
> memory and unnecessary casting in later patches.
Thanks for the comments!
Do you mean doing it like the following?
struct irte {
union {
struct {
__u64 present : 1,
fpd : 1,
dst_mode : 1,
redir_hint : 1,
trigger_mode : 1,
dlvry_mode : 3,
avail : 4,
__reserved_1 : 4,
vector : 8,
__reserved_2 : 8,
dest_id : 32;
};
struct {
__u64 present : 1,
fpd : 1,
__reserved_1 : 6,
avail : 4,
__reserved_2 : 2,
urg : 1,
pst : 1,
vector : 8,
__reserved_3 : 14,
pda_l : 26;
};
__u64 low;
};
union {
struct {
__u64 sid : 16,
sq : 2,
svt : 2,
__reserved_3 : 44;
};
struct {
__u64 sid : 16,
sq : 2,
svt : 2,
__reserved_4 : 12,
pda_h : 32;
};
__u64 high;
};
};
In fact, I also intended to make these two defines as one, however, this code
will get build
error ("duplicated member") with new version of GCC, such as, gcc 4.9.1. I
cannot find a
good way to handle this gracefully, since I don't want to impact the existing
usage of this
structure . Do you have any ideas about this? Thanks a lot!
Thanks,
Feng
>
>
> Joerg
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