From: Avi Kivity <avi@redhat.com>
To: Zhi Yong Wu <zwu.kernel@gmail.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>,
Anthony Liguori <aliguori@us.ibm.com>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] memory: Why subpage is introduced?
Date: Wed, 21 Dec 2011 15:30:57 +0200 [thread overview]
Message-ID: <4EF1DF91.3020905@redhat.com> (raw)
In-Reply-To: <CAEH94Lj3Cuu__RTtoYfbEZK1f44DvxLFFHhuAA9-N-1Aq5iZpA@mail.gmail.com>
On 12/21/2011 02:09 PM, Zhi Yong Wu wrote:
> HI,
>
> For memory management, i have several questions as below:
>
> 1.) Why is subpage introduced? what is its goal?
A TLB entry spans one page; a subpage is a way of dispatching accesses
through that tlb entry to various memory regions.
> 2.) How to render MemoryRegion into one disjoint flatrange list? That
> rendering function is a bit difficult to understand. Can anyone simply
> explain it?
What exactly don't you understand?
>
> 3.) What are separately the meanings of these flags? such as
> IO_MEM_RAM, IO_MEM_ROM, IO_MEM_UNASSIGNED, IO_MEM_*, IO_MEM_ROMD, and
> IO_MEM_SUBPAGE.
RAM = RAM
ROM = ROM
UNASSIGNED = nothing handles this range
ROMD = ROM when read, device (i.e. callbacks) when written
SUBPAGE = dispatch using the lower address bits to obtain final I/O handler.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2011-12-21 13:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-21 12:09 [Qemu-devel] memory: Why subpage is introduced? Zhi Yong Wu
2011-12-21 13:30 ` Avi Kivity [this message]
2011-12-22 11:24 ` Zhi Yong Wu
2011-12-22 12:38 ` Avi Kivity
2011-12-23 5:56 ` Zhi Yong Wu
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