On Thu, Jun 23, 2022 at 04:47:22PM +0200, Jan Beulich wrote: > On 23.06.2022 10:24, Roger Pau Monne wrote: > > Allow selecting the default x2APIC destination mode from Kconfig. > > Note the default destination mode is still Logical (Cluster) mode. > > > > Signed-off-by: Roger Pau Monné <roger....@citrix.com> > > --- > > xen/arch/x86/Kconfig | 29 +++++++++++++++++++++++++++++ > > xen/arch/x86/genapic/x2apic.c | 6 ++++-- > > 2 files changed, 33 insertions(+), 2 deletions(-) > > > > diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig > > index 1e31edc99f..f560dc13f4 100644 > > --- a/xen/arch/x86/Kconfig > > +++ b/xen/arch/x86/Kconfig > > @@ -226,6 +226,35 @@ config XEN_ALIGN_2M > > > > endchoice > > > > +choice > > + prompt "x2APIC default destination mode" > > What's the point of using "choice" here, and not a single "bool"?
I think choice better reflects the purpose of the option, it's selecting between two different modes. It could be expressed with a bool, but I think it's less clear. > > + default X2APIC_LOGICAL > > + ---help--- > > Nit: Please don't use ---help--- anymore - we're trying to phase out its > use as Linux has dropped it altogether (and hence once we update our > Kconfig, we'd like to change as few places as possible), leaving just > "help". > > One downside of "choice" (iirc) is that the individual sub-options' help > text is inaccessible from at least the command line version of kconfig. Hm, I usually use menuconfig when wanting to poke at options help. I guess I could introduce a single X2APIC_PHYSICAL bool that starts with default false and notes that otherwise the destination mode is logical. > > + Specify default destination mode for x2APIC. > > + > > + If unsure, choose "Logical". > > + > > +config X2APIC_LOGICAL > > + bool "Logical mode" > > + ---help--- > > + Use Logical Destination mode. > > + > > + When using this mode APICs are addressed using the Logical > > + Destination mode, which allows for optimized IPI sending, > > + but also reduces the amount of vectors available for external > > + interrupts when compared to physical mode. > > + > > +config X2APIC_PHYS > > X2APIC_PHYSICAL (to be in line with X2APIC_LOGICAL)? Right, was about to expand it but did consider PHYS to be clear enough (opposed to using LOG or LOGIC), will expand in next version. Thanks, Roger.
