Re: [Xen-devel] [PATCH v2 01/23] x86/boot: remove unneeded instruction

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Fri, Jul 24, 2015 at 12:22:57PM -0400, Konrad Rzeszutek Wilk wrote:
> On Mon, Jul 20, 2015 at 04:28:56PM +0200, Daniel Kiper wrote:
> > Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
>
> Don't you use it in:
>
>     /* Switch to low-memory stack.  */
> 193         mov     sym_phys(trampoline_phys),%edi
> 194         lea     0x10000(%edi),%esp
> 195         lea     trampoline_boot_cpu_entry-trampoline_start(%edi),%eax
> ?

Yep, but...

> > ---
> >  xen/arch/x86/boot/head.S |    1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
> > index cfd59dc..f63b349 100644
> > --- a/xen/arch/x86/boot/head.S
> > +++ b/xen/arch/x86/boot/head.S
> > @@ -169,7 +169,6 @@ __start:
> >          /* Apply relocations to bootstrap trampoline. */
> >          mov     sym_phys(trampoline_phys),%edx

...relevant value is stored in sym_phys(trampoline_phys) earlier then it is
read into %edx here and...

> >          mov     $sym_phys(__trampoline_rel_start),%edi
> > -        mov     %edx,sym_phys(trampoline_phys)

...it is put back to sym_phys(trampoline_phys) without any change here :-))).
So, I suppose this is remnant from something which was removed once but
somebody forgot to remove this instruction too... This patch fixes it.

Daniel

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