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

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Fri, Oct 17, 2014 at 04:00:57PM +0100, Andrew Cooper wrote:
> On 17/10/14 15:11, Daniel Kiper wrote:
> > ..to access multiboot.mem_lower data.
> >
> > Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
>
> 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.

MB_* stuff is removed by patch #6. Later we have MBD_*, MBI_* and MBI2_* only.

Daniel

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