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Date: Tue, 14 Feb 2012 16:11:57 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH RFC] seabios: add OSHP method stub
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To: Paul Brook <paul@codesourcery.com>
Cc: Kevin Wolf <kwolf@redhat.com>, kvm@vger.kernel.org, seabios@seabios.org, qemu-devel@nongnu.org, Isaku Yamahata <yamahata@valinux.co.jp>, Kevin O'Connor <kevin@koconnor.net>, Avi Kivity <avi@redhat.com>

On Tue, Feb 14, 2012 at 01:47:59PM +0000, Paul Brook wrote:
> > > > Now an OS can have a standard driver and use it
> > > > to activate hotplug functionality. This is OS hotplug (OSHP).
> > > 
> > > So presumably this will work on targets that don't have ACPI?
> > > Assuming a competent guest OS of course.  Have you tested this?
> > 
> > This being the qemu side of things? I run Linux
> > and verified that it calls OSHP and afterwards,
> > runs the native driver and handles hotplug/unplug
> > without invoking ACPI at all.
> 
> I mean using your shiny new hotplug PCI-PCI bridge on arm/ppc/mips targets 
> (i.e anything other than x86 PC).  From your description it sounds like it 
> *should* work.
>  
> > It seems that at least the SHPC driver in linux
> > doesn't work if you don't have an acpi table
> > with the OSHP method - not many people run with acpi=off
> > nowdays, so it's probably just a bug.
> > I'll check how hard it is to fix this.
> 
> Targets other than x86 don't have ACPI to start with.
> 
> Paul

So

#ifdef CONFIG_ACPI
#include <linux/pci-acpi.h>
static inline int get_hp_hw_control_from_firmware(struct pci_dev *dev)
{
        u32 flags = OSC_SHPC_NATIVE_HP_CONTROL;
        return acpi_get_hp_hw_control_from_firmware(dev, flags);
}
#else
#define get_hp_hw_control_from_firmware(dev) (0)
#endif

So if you build your guest without acpi, things should work fine.

-- 
MMST