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 13:09, <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> > 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.
> 
> Okay. Then how about making _VECTOR x86-specific, and the
> new one ARM-specific (via #ifdef), at once allowing (if so
> wanted) both to share the same numeric value?

Fine by me

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