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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.04.14 at 21:50, <andrew.cooper3@xxxxxxxxxx> wrote:
> --- 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

The longer the code sequences between branch and label, the less
desirable is the use of such numeric ones. Please use .Lhalt or some
such instead here.

Jan


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