From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.fraser@eu.citrix.com>
Subject: Re: Baffled by multipage_allocation_permitted()
Date: Mon, 15 Jun 2009 22:57:03 +0100
Message-ID: <C65C823F.D4FF%keir.fraser@eu.citrix.com>
References: <200906151644.51978.dcm@mccr.org>
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To: Dave McCracken <dcm@mccr.org>, Xen Developers List <xen-devel@lists.xensource.com>
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On 15/06/2009 22:44, "Dave McCracken" <dcm@mccr.org> wrote:

> #define multipage_allocation_permitted(d)   \
>    (!rangeset_is_empty((d)->iomem_caps) || \
>     !rangeset_is_empty((d)->arch.ioport_caps))
> 
> I had never tracked down the significance of this macro since it didn't appear
> to be an issue.  Now it's suddenly denying me the ability to work in 2M pages.
> 
> What is this macro trying to achieve?  Why is it necessary?  Is there any
> compelling reason we can't just remove it and allow multipage allocations from
> any domain?

We can just get rid of it I think. There are arguably worse other things we
already allow, like any guest can allocate low memory by specifying a small
value of XENMEMF_address_bits().

 -- Keir