Re: [PATCH 3/5] X86/XEN: Introduce the x86_init.paging.pagetable_initPVOPS

[Attilio Rao]

On 21/08/12 16:44, Thomas Gleixner wrote:
> On Tue, 21 Aug 2012, Attilio Rao wrote:
>
>    
> > This new PVOPS is responsible to setup the kernel pagetables and
> > replace entirely x86_init.paging.pagetable_setup_start and
> > x86_init.paging.pagetable_setup_done PVOPS work.
> >      
>
>    
> > For performance the x86_64 stub is implemented as a macro to paging_init()
> > rather than an actual function stub.
> >      
> Huch, using a macro for an once per boot time call is really a massive
> performance improvement.
>
> It's confusing and wrong. You just use a macro because x86_64 does not
> need any extra setups aside of paging_init().
>
>    
> > diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
> > index 849be14..c1e910a 100644
> > --- a/arch/x86/kernel/x86_init.c
> > +++ b/arch/x86/kernel/x86_init.c
> > @@ -68,6 +68,7 @@ struct x86_init_ops x86_init __initdata = {
> >   	},
> >
> >   	.paging = {
> > +		.pagetable_init		= native_pagetable_init,
> >      
> I'd prefer to see these patches implemented differently.
>
>   #1 Remove the base argument from pagetable_setup_start (leave
>      pagetable_setup_done() alone).
>
>   #2 Rename pagetable_setup_start to pagetable_init,
>      native_pagetable_setup_start to native_pagetable_init and
>      xen_pagetable_setup_start to xen_pagetable_init
>
>   #3 Instead of copying the whole native_pagetable_setup_start()
>      function and deleting it later, move the paging_init() call from
>      setup.c to native_pagetable_init() and xen_pagetable_init()
>      and define native_pagetable_init as paging_init() for x86_64
>
>   #4 Move the code from xen_pagetable_setup_done() into
>      xen_pagetable_init() and remove the now unused
>      pagetable_setup_done().
>
> That's less code shuffling and pointless copying which makes the
> review way easier.
>    

I've followed these steps in a new patch series (integrating suggestions 
from Konrad and Stefano too).

Attilio
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