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Date: Mon, 25 Jan 2010 16:17:02 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Mike Travis <travis@sgi.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>, Ingo Molnar <mingo@elte.hu>,
       Russ Anderson <rja@sgi.com>, Dave Airlie <airlied@redhat.com>,
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       Robin Holt <holt@sgi.com>, "Rafael J. Wysocki" <rjw@sisk.pl>,
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       linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH 1/4] pci: Update pci_set_vga_state to call arch
 functions
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On Mon, 25 Jan 2010 16:09:52 -0800
Mike Travis <travis@sgi.com> wrote:

> > 
> > Still, a neater solution might be
> > 
> > int arch_pci_set_vga_state(...) __weak
> > {
> > 	return 0;
> > }
> > 
> > and then resolve it at linkage time?
> > 
> > 
> 
> Wouldn't the linked in stronger function then need to surround
> the UV register updating with "if (uv_system)"?

If the file which implements arch_pci_set_vga_state() is present in
vmlinux on non-uv systems then yes.

Presumably that file is arch/x86/kernel/apic/x2apic_uv_x.c, although
that might later become a problem if other sub-architectures a) want to
get at this hook and b) can be linked into vmlinux along with
arch/x86/kernel/apic/x2apic_uv_x.o.  But such a kernel wouldn't
actually link, so we'll need to address it at that stage.


If this is a UV-specific hack which other architectures and
sub-architectures are unlikely to need (seems that way?) then I'd be
going for something whcih is simple and minimal.