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.
Juergen