#include /* * __force_order is used by special_insns.h asm code to force instruction * serialization. * * It is not referenced from the code, but GCC < 5 with -fPIE would fail * due to an undefined symbol. Define it to make these ancient GCCs work. */ unsigned long __force_order; int l5_paging_required(void) { /* Check if leaf 7 is supported. */ if (native_cpuid_eax(0) < 7) return 0; /* Check if la57 is supported. */ if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) return 0; /* Check if 5-level paging has already been enabled. */ if (native_read_cr4() & X86_CR4_LA57) return 0; return 1; }