On Thu, Jan 25, 2018 at 11:49:35AM +0100, Juergen Gross wrote:
> On 25/01/18 11:37, Greg KH wrote:
> > On Thu, Jan 25, 2018 at 11:04:54AM +0100, Juergen Gross wrote:
> >> Add acpi_arch_get_root_pointer() for Xen PVH guests to communicate
> >> the address of the RSDP table given to the kernel via Xen start info.
> >>
> >> This makes the kernel boot again in PVH mode after on recent Xen the
> >> RSDP was moved to higher addresses. So up to that change it was pure
> >> luck that the legacy method to locate the RSDP was working when
> >> running as PVH mode.
> >>
> >> Cc: <stable@xxxxxxxxxxxxxxx> # 4.11
> >> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> >> ---
> >> arch/x86/xen/enlighten_pvh.c | 15 ++++++++++++---
> >> 1 file changed, 12 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
> >> index 436c4f003e17..9a5c3a7fe673 100644
> >> --- a/arch/x86/xen/enlighten_pvh.c
> >> +++ b/arch/x86/xen/enlighten_pvh.c
> >> @@ -16,15 +16,24 @@
> >> /*
> >> * PVH variables.
> >> *
> >> - * xen_pvh and pvh_bootparams need to live in data segment since they
> >> - * are used after startup_{32|64}, which clear .bss, are invoked.
> >> + * xen_pvh, pvh_bootparams and pvh_start_info need to live in data segment
> >> + * since they are used after startup_{32|64}, which clear .bss, are invoked.
> >> */
> >> bool xen_pvh __attribute__((section(".data"))) = 0;
> >> struct boot_params pvh_bootparams __attribute__((section(".data")));
> >> +struct hvm_start_info pvh_start_info __attribute__((section(".data")));
> >>
> >> -struct hvm_start_info pvh_start_info;
> >> unsigned int pvh_start_info_sz = sizeof(pvh_start_info);
> >>
> >> +acpi_physical_address acpi_arch_get_root_pointer(void)
> >> +{
> >> + if (xen_pvh)
> >> + return pvh_start_info.rsdp_paddr;
> >> +
> >> + return 0;
> >> +}
> >> +EXPORT_SYMBOL_GPL(acpi_arch_get_root_pointer);
> >
> > Why does this have to be an exported symbol? Does this code get built
> > as a module and will the linker somehow go and rewrite the previous call
> > places with this one if it gets loaded?
>
> With being called by drivers/acpi/... I just wanted to make sure it is
> working properly even in case the acpi code is built as a module.
I didn't think the core ACPI code can be built as a module, have you
tried that?
thanks,
greg k-h
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