Re: [Xen-devel] [PATCH v3 04/10] Make MEM_ACCESS configurable

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 29 May 2018, Jan Beulich wrote:
> >>> On 23.05.18 at 02:25, <sstabellini@xxxxxxxxxx> wrote:
> > --- a/xen/arch/arm/Kconfig
> > +++ b/xen/arch/arm/Kconfig
> > @@ -26,6 +26,9 @@ config ARCH_DEFCONFIG
> >     default "arch/arm/configs/arm32_defconfig" if ARM_32
> >     default "arch/arm/configs/arm64_defconfig" if ARM_64
> >  
> > +config HAS_MEM_ACCESS
> > +   def_bool y
> 
> The more that you're not deleting the respective select-s, please
> don't introduce such per-arch. Keep the arch-neutral one, ...

OK


> > @@ -30,6 +31,12 @@ config ARCH_DEFCONFIG
> >     string
> >     default "arch/x86/configs/x86_64_defconfig"
> >  
> > +config HAS_MEM_ACCESS
> > +   def_bool y
> > +
> > +config MEM_ACCESS_ALWAYS_ON
> > +   def_bool y
> 
> ... make this one similarly an arch-neutral one (select-ed further up
> in this file).

OK


> > --- a/xen/common/Kconfig
> > +++ b/xen/common/Kconfig
> > @@ -20,8 +20,15 @@ config HAS_DEVICE_TREE
> >  config HAS_EX_TABLE
> >     bool
> >  
> > -config HAS_MEM_ACCESS
> > +config MEM_ACCESS
> >     bool
> > +   prompt "Memory Access and VM events" if !MEM_ACCESS_ALWAYS_ON
> > +   default y
> 
> Please combine bool and default to def_bool.

OK


> Also - do we perhaps want the
> prompt to additionally have an EXPERT dependency? Without you saying why
> you want this configurable I can't tell whether this would make sense.

I am doing this mostly to reduce the code size. I think we should
security support configurations without MEM_ACCESS. I also don't think
it should take an "expert" to disable MEM_ACCESS in Xen. Thus, my
preference is to avoid adding the EXPERT dependency.

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