From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: Xen/pv_ops features/patches for 2.6.29? (updating
	wiki)
Date: Fri, 13 Feb 2009 11:30:35 -0800
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To: "Nakajima, Jun" <jun.nakajima@intel.com>
Cc: "bderzhavets@yahoo.com" <bderzhavets@yahoo.com>, "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
List-Id: xen-devel@lists.xenproject.org

Nakajima, Jun wrote:
> I noticed that the changes like
>         if (xen_initial_domain())
>                 ...
>
> For example,
> static inline unsigned int io_apic_read(unsigned int apic, unsigned int reg)
> {
>         struct io_apic __iomem *io_apic;
>
>         if (xen_initial_domain())
>                 return xen_io_apic_read(apic, reg);
>
>         io_apic = io_apic_base(apic);
>         writel(reg, &io_apic->index);
>         return readl(&io_apic->data);
> }
>
>
> Do you think those need to be wrapped by pv_ops? Probably it's better to replace such functions (e.g. io_apic_read/write) with Xen-specific ones, rather than adding hooks.
>   

That's been a point of contention.  Originally I had some io_apic_ops to 
do that, but I got pushback.  The current patch is more to make a point 
than something I'd expect to be upstreamed (but who knows?).  It isn't 
actually too bad this way, because xen_initial_domain() compiles down to 
a constant 0 if CONFIG_XEN_DOM0 is disabled, and its just a test of a 
variable if its enabled.

    J