Re: [Xen-devel] [PATCH v5 19/22] hvm/params: Add a new delivery type for event-channel in HVM_PARAM_CALLBACK_IRQ

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 4 Mar 2016, Jan Beulich wrote:
> >>> On 04.03.16 at 07:15, <zhaoshenglong@xxxxxxxxxx> wrote:
> > From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> > 
> > Add a new delivery type:
> > val[63:56] == 3: val[15:8] is flag: val[7:0] is a PPI.
> > To the flag, bit 8 stands the interrupt mode is edge(1) or level(0) and
> > bit 9 stands the interrupt polarity is active low(1) or high(0).
> > 
> > Cc: Jan Beulich <jbeulich@xxxxxxxx>
> > Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> 
> The set of Cc-s is too narrow - all REST maintainers should be copied.
> 
> > --- a/xen/include/public/hvm/params.h
> > +++ b/xen/include/public/hvm/params.h
> > @@ -55,6 +55,16 @@
> >   * if this delivery method is available.
> >   */
> >  
> > +#define HVM_PARAM_CALLBACK_TYPE_EVENT    3
> > +/*
> > + * val[55:16] need to be zero.
> > + * val[15:8] is flag of event-channel interrupt:
> > + *  bit 8: interrupt is edge(1) or level(0) triggered
> > + *  bit 9: interrupt is active low(1) or high(0)
> > + * val[7:0] is PPI number used by event-channel.
> > + * This is only used by ARM/ARM64.
> > + */
> 
> I think the name of the constant needs improvement. The low 8
> bits make this extremely ARM specific, so perhaps
> HVM_PARAM_CALLBACK_TYPE_PPI?

That would be OK for me.


> Albeit - wouldn't the
> vector and/or GSI ones be re-usable for this purpose? (I
> don't know enough about ARM to be certain.)

Vector is an x86 thing, while GSI is an ACPI term. There is probably a
PPI to GSI mapping on ARM ACPI systems, but I wouldn't want this
HVM_PARAM to work only with ACPI: it should work with device tree
systems too, where GSI has no meaning.


> And then I'm now also wondering about the description of bits
> 8 and 9 - event channels don't know of edge/level triggering
> or high/low polarity, so it looks to me as if the comment is at
> least misleading too.

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