Re: [Xen-devel] [PATCH v2 05/10] libxl/xl: add memory policy option to iomem

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 18 Jun 2019, Julien Grall wrote:
> On 30/04/2019 22:02, Stefano Stabellini wrote:
> > diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> > index 89fe80f..a6c5e30 100644
> > --- a/tools/libxl/libxl_create.c
> > +++ b/tools/libxl/libxl_create.c
> > @@ -415,6 +415,21 @@ static void init_console_info(libxl__gc *gc,
> >          Only 'channels' when mapped to consoles have a string name. */
> >   }
> >   +static uint32_t libxl__memory_policy_to_xc(libxl_memory_policy c)
> > +{
> > +    switch (c) {
> > +    case LIBXL_MEMORY_POLICY_ARM_MEM_WB:
> > +        return MEMORY_POLICY_ARM_MEM_WB;
> > +    case LIBXL_MEMORY_POLICY_ARM_DEV_NGRE:
> > +        return MEMORY_POLICY_ARM_DEV_nGRE;
> > +    case LIBXL_MEMORY_POLICY_X86_UC:
> > +        return MEMORY_POLICY_X86_UC;
> > +    case LIBXL_MEMORY_POLICY_DEFAULT:
> > +    default:
> 
> Looking at this again, don't we want to bail out if the policy is unknown? My
> concern here is the user may configure with something it didn't expect. The
> risk is the problem will be hard to debug.
> 
> I also believe this could be part of libxl_{arm,x86}.c allowing us to filter
> misuse early.

This sounds like a good idea, I can do that. Then, I can also #ifdef the
hypercalls defines, although for some reason today libxl doesn't have
CONFIG_X86 or CONFIG_ARM set so I would also have to do the following in
the libxl Makefile:

ifeq ($(CONFIG_X86),y)
CFLAGS_LIBXL += -DCONFIG_X86
else
CFLAGS_LIBXL += -DCONFIG_ARM
endif


> Ian, Wei, any opinion?

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