[PATCH v2 3/3] x86/boot: Use 'hlt' inside terminal loops

[Andrew Cooper <andrew.cooper3@citrix.com>]

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Keir Fraser <keir@xen.org>
CC: Jan Beulich <JBeulich@suse.com>

---
v2: Use '.Lhalt' in preference to '3f'
---
 xen/arch/x86/boot/head.S   |    8 +++++---
 xen/arch/x86/boot/x86_64.S |    3 ++-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 0d87b27..ca0e97d 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -54,11 +54,11 @@ print_err:
         mov     $0xB8000,%edi  # VGA framebuffer
 1:      mov     (%esi),%bl
         test    %bl,%bl        # Terminate on '\0' sentinel
-2:      je      2b
+        je      .Lhalt
         mov     $0x3f8+5,%dx   # UART Line Status Register
-3:      in      %dx,%al
+2:      in      %dx,%al
         test    $0x20,%al      # Test THR Empty flag
-        je      3b
+        je      2b
         mov     $0x3f8+0,%dx   # UART Transmit Holding Register
         mov     %bl,%al
         out     %al,%dx        # Send a character over the serial line
@@ -66,6 +66,8 @@ print_err:
         mov     $7,%al
         stosb                  # Write an attribute to the VGA framebuffer
         jmp     1b
+.Lhalt: hlt
+        jmp     .Lhalt
 
 __start:
         cld
diff --git a/xen/arch/x86/boot/x86_64.S b/xen/arch/x86/boot/x86_64.S
index 7ecfad3..fe5469a 100644
--- a/xen/arch/x86/boot/x86_64.S
+++ b/xen/arch/x86/boot/x86_64.S
@@ -73,7 +73,8 @@ ignore_int:
         call    printk
         testq   $0xff8,%rbp
         jnz     0b
-1:      jmp     1b
+1:      hlt
+        jmp     1b
 
         .section .init.rodata, "a", @progbits
 
-- 
1.7.10.4