diff options
| -rw-r--r-- | arch/x86/machine/boot_asm.S | 24 | ||||
| -rw-r--r-- | arch/x86/machine/cpu.h | 2 |
2 files changed, 26 insertions, 0 deletions
diff --git a/arch/x86/machine/boot_asm.S b/arch/x86/machine/boot_asm.S index ce377442..85441f70 100644 --- a/arch/x86/machine/boot_asm.S +++ b/arch/x86/machine/boot_asm.S @@ -64,6 +64,7 @@ ENTRY(_start) movl %esp, %ebp #ifdef __LP64__ + call boot_check_long_mode call boot_setup_long_mode /* @@ -105,9 +106,32 @@ DATA(boot_gdtr) END(boot_gdtr) #ifdef __LP64__ + /* * The %eax and %ebx registers must be preserved. */ + +ENTRY(boot_check_long_mode) + pushl %eax + pushl %ebx + movl $0x80000000, %eax + cpuid + cmpl $0x80000000, %eax + jbe boot_no_long_mode + movl $0x80000001, %eax + cpuid + testl $CPU_FEATURE4_LM, %edx + jz boot_no_long_mode + popl %ebx + popl %eax + ret +END(boot_check_long_mode) + +ENTRY(boot_no_long_mode) + hlt + jmp boot_no_long_mode +END(boot_no_long_mode) + ENTRY(boot_setup_long_mode) /* Set PML4[0] */ movl $boot_pdpt, %edx diff --git a/arch/x86/machine/cpu.h b/arch/x86/machine/cpu.h index db847c68..bfb5abe0 100644 --- a/arch/x86/machine/cpu.h +++ b/arch/x86/machine/cpu.h @@ -64,6 +64,8 @@ #define CPU_FEATURE2_APIC 0x00000200 #define CPU_FEATURE2_PGE 0x00002000 +#define CPU_FEATURE4_LM 0x20000000 + /* * Model specific registers. */ |