AcpiOsGetRootPointer
if ((rsdp_ptr = AcpiOsGetRootPointer()) == 0)
if ((rsdp_ptr = AcpiOsGetRootPointer()) == 0)
has_acpi = (AcpiOsGetRootPointer() != 0);
if ((paddr = AcpiOsGetRootPointer()) == 0 ||
if ((rsdp_ptr = AcpiOsGetRootPointer()) == 0)