Re: [PATCH for-xen-4.5 v4 04/18] x86/boot: use constant in head.S instead of hardcoded value

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

On 17/10/14 15:11, Daniel Kiper wrote:
> ..to access multiboot.mem_lower data.
>
> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>

Fine, but...

> ---
>  xen/arch/x86/boot/head.S          |    2 +-
>  xen/arch/x86/x86_64/asm-offsets.c |    3 +++
>  2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
> index cd43952..0bdbc65 100644
> --- a/xen/arch/x86/boot/head.S
> +++ b/xen/arch/x86/boot/head.S
> @@ -101,7 +101,7 @@ __start:
>           */
>          testb   $MBI_MEMLIMITS,(%ebx)
>          jz      2f                  /* not available? BDA value will be fine */
> -        mov     4(%ebx),%edx
> +        mov     MBI_mem_lower(%ebx),%edx
>          cmp     $0x100,%edx         /* is the multiboot value too small? */
>          jb      2f                  /* if so, do not use it */
>          shl     $10-4,%edx
> diff --git a/xen/arch/x86/x86_64/asm-offsets.c b/xen/arch/x86/x86_64/asm-offsets.c
> index 3994f4d..2de9cad 100644
> --- a/xen/arch/x86/x86_64/asm-offsets.c
> +++ b/xen/arch/x86/x86_64/asm-offsets.c
> @@ -163,6 +163,9 @@ void __dummy__(void)
>      OFFSET(CPUINFO_features, struct cpuinfo_x86, x86_capability);
>      BLANK();
>  
> +    OFFSET(MBI_mem_lower, multiboot_info_t, mem_lower);
> +    BLANK();
> +
>      OFFSET(MB_flags, multiboot_info_t, flags);
>      OFFSET(MB_cmdline, multiboot_info_t, cmdline);

These are derived from the same struct, so should be declared together,
and have consistent naming.

~Andrew