linux-kernel - Re: [RFC 8/8] x86_64: Support for new UV apic

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Date:	Wed, 26 Mar 2008 00:24:02 -0300
From:	"Glauber Costa" <glommer@...il.com>
To:	"Jack Steiner" <steiner@....com>
Cc:	"Ingo Molnar" <mingo@...e.hu>, tglx@...utronix.de,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC 8/8] x86_64: Support for new UV apic

On Tue, Mar 25, 2008 at 1:31 PM, Jack Steiner <steiner@....com> wrote:
> On Tue, Mar 25, 2008 at 03:30:59PM +0100, Ingo Molnar wrote:
>  >
>  > * Jack Steiner <steiner@....com> wrote:
>  >
>  > > Index: linux/arch/x86/kernel/genapic_64.c
>  >
>  > > @@ -69,7 +73,16 @@ void send_IPI_self(int vector)
>  > >
>  > >  unsigned int get_apic_id(void)
>  > >  {
>  > > -   return (apic_read(APIC_ID) >> 24) & 0xFFu;
>  > > +   unsigned int id;
>  > > +
>  > > +   preempt_disable();
>  > > +   id = apic_read(APIC_ID);
>  > > +   if (uv_system_type >= UV_X2APIC)
>  > > +           id  |= __get_cpu_var(x2apic_extra_bits);
>  > > +   else
>  > > +           id = (id >> 24) & 0xFFu;;
>  > > +   preempt_enable();
>  > > +   return id;
>  >
>  > dont we want to put get_apic_id() into struct genapic instead? We
>  > already have ID management there.
>  >
>  > also, we want to unify 32-bit and 64-bit genapic code and just have
>  > genapic all across x86.
>
>  Long term, I think that makes sense. However, I think that should be a
>  separate series of patches since there are significant differences between
>  the 32-bit and 64-bit genapic structs.
>
However, if you add more code, they'll keep diverging. The moment you
touch them, and get your
hands warmed up, is the perfect moment for an integration series.

-- 
Glauber Costa.
"Free as in Freedom"
http://glommer.net

"The less confident you are, the more serious you have to act."
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