From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.fraser@eu.citrix.com>
Subject: Re: How to determine memory size in HVM
Date: Wed, 10 Jun 2009 09:24:11 +0100
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To: James Harper <james.harper@bendigoit.com.au>, "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
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On 09/06/2009 08:42, "James Harper" <james.harper@bendigoit.com.au> wrote:

> memory/target = 786432KB
> XENMEM_current_reservation = 198623 pages
> 
> 198623 << PAGE_SHIFT = 794492KB
> 794492KB - 786432KB = 8060KB
> 
> So I have 8060KB unaccounted for... I guess that's probably the
> framebuffer. According to Device Manager in Windows, the CL5446 device
> uses 64KB of memory at 0xA0000, 32MB at 0xF0000000, and 4KB at
> 0xF3000000. That's more than the extra 8MB, but it would make sense that
> the 32MB wouldn't all be mapped in if it wasn't required.

Yes, that's the framebuffer. It is variable size, in principle, though. I'm
not sure you can do better than read XENMEM_current_reservation and
memory/target at driver startup time, and keep the delta between them
constant.

 -- Keir