[Xen-devel] [PATCH 4/4] x86/boot: Use 'hlt' inside terminal loops

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
---
 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 d706c44..06014ec 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -52,11 +52,11 @@ print_err:
         mov     $0xB8000,%edi  # VGA framebuffer
 1:      mov     (%esi),%bl
         test    %bl,%bl        # Terminate on '\0' sentinel
-2:      je      2b
+        je      3f
         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
@@ -64,6 +64,8 @@ print_err:
         mov     $7,%al
         stosb                  # Write an attribute to the VGA framebuffer
         jmp     1b
+3:      hlt
+        jmp     3b
 
 __start:
         cld
diff --git a/xen/arch/x86/boot/x86_64.S b/xen/arch/x86/boot/x86_64.S
index 0c086b2..fd3d93a 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.data, "aw", @progbits
 
-- 
1.7.10.4


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