Re: [Xen-devel] [PATCH] xen/shim: stash RSDP address for ACPI driver

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Jan 22, 2018 at 06:35:14AM -0700, Jan Beulich wrote:
> >>> On 22.01.18 at 14:21, <wei.liu2@xxxxxxxxxx> wrote:
> > On Mon, Jan 22, 2018 at 01:03:14PM +0000, Roger Pau Monné wrote:
> >> On Mon, Jan 22, 2018 at 12:47:10PM +0000, Wei Liu wrote:
> >> > --- a/xen/drivers/acpi/osl.c
> >> > +++ b/xen/drivers/acpi/osl.c
> >> > @@ -38,6 +38,10 @@
> >> >  #include <xen/efi.h>
> >> >  #include <xen/vmap.h>
> >> >  
> >> > +#ifdef CONFIG_PVH_GUEST
> >> > +#include <asm/guest/pvh-boot.h>
> >> > +#endif
> >> > +
> >> >  #define _COMPONENT              ACPI_OS_SERVICES
> >> >  ACPI_MODULE_NAME("osl")
> >> >  
> >> > @@ -74,6 +78,11 @@ acpi_physical_address __init 
> >> > acpi_os_get_root_pointer(void)
> >> >                                 "System description tables not found\n");
> >> >                          return 0;
> >> >                  }
> >> > +#ifdef CONFIG_PVH_GUEST
> >> > +        } else if (pvh_boot) {
> >> > +                ASSERT(pvh_rsdp_pa);
> >> > +                return pvh_rsdp_pa;
> >> > +#endif
> >> >          } else if (IS_ENABLED(CONFIG_ACPI_LEGACY_TABLES_LOOKUP)) {
> >> >                  acpi_physical_address pa = 0;
> >> 
> >> Can this be done in a non-PVH specific way?
> >> 
> >> Can we have a global rsdp_hint variable or similar that would be used
> >> here if set?
> > 
> > Who will be the anticipated user(s) other than PVH?
> 
> That's not so much the question here imo. Instead the issue I
> see is that the way you code it it's really a layering violation.
> Similar hackery was also rejected in Linux recently, iirc.
> 

OK. I buy this argument.

Let me invent a rsdp_hint instead.

Wei.

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