From: Anthony Liguori <anthony@codemonkey.ws>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Avi Kivity <avi@redhat.com>, kvm@vger.kernel.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [RFC v2 00/20] Memory API
Date: Mon, 27 Jun 2011 15:28:05 -0500 [thread overview]
Message-ID: <4E08E7D5.4000207@codemonkey.ws> (raw)
In-Reply-To: <20110627155920.GB5614@redhat.com>
On 06/27/2011 10:59 AM, Michael S. Tsirkin wrote:
> On Mon, Jun 27, 2011 at 06:54:05PM +0300, Avi Kivity wrote:
>> On 06/27/2011 06:52 PM, Michael S. Tsirkin wrote:
>>> - bridges might also enable subtractive decoding
>>> (required for isa behind the bridge)
>>
>> What does that mean?
>
> subtractive decoding is
> a method of address decoding in which a device accepts all
> accesses not positively decoded by another agent.
Subtractive decoding is very slow in real hardware so generally any well
known devices are positively decoded (like anything on the Super I/O
chip). Unless we're dealing with very odd ISA devices, we probably
don't need to worry about subtractive decoding.
The real key point is, each level may dispatch in subtly different ways.
You can get 95% of the way there with a generic memory API. I think
it's the 95% that actually matters but just realize that we can't model
hardware exactly without true hierarchical dispatch.
Regards,
Anthony Liguori
next prev parent reply other threads:[~2011-06-27 20:28 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-27 13:21 [Qemu-devel] [RFC v2 00/20] Memory API Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 01/20] Hierarchical memory region API Avi Kivity
2011-06-28 10:03 ` Michael S. Tsirkin
2011-06-28 10:28 ` Jan Kiszka
2011-06-28 11:53 ` Avi Kivity
2011-06-28 12:07 ` Jan Kiszka
2011-06-28 12:09 ` Avi Kivity
2011-06-28 12:46 ` Jan Kiszka
2011-06-28 12:53 ` Avi Kivity
2011-06-28 13:25 ` Peter Maydell
2011-06-28 13:36 ` Avi Kivity
2011-06-28 16:27 ` Olivier Galibert
2011-06-28 11:51 ` Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 02/20] memory: implement dirty tracking Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 03/20] memory: merge adjacent segments of a single memory region Avi Kivity
2011-06-27 13:56 ` Jan Kiszka
2011-06-27 14:11 ` Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 04/20] Internal interfaces for memory API Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 05/20] exec.c: initialize memory map Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 06/20] pc: grab system_memory Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 07/20] pc: convert pc_memory_init() to memory API Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 08/20] pc: move global memory map out of pc_init1() and into its callers Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 09/20] pci: pass address space to pci bus when created Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 10/20] pci: add MemoryRegion based BAR management API Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 11/20] sysbus: add MemoryRegion based memory " Avi Kivity
2011-06-27 13:21 ` [Qemu-devel] [RFC v2 12/20] usb-ohci: convert to MemoryRegion Avi Kivity
2011-06-27 13:22 ` [Qemu-devel] [RFC v2 13/20] pci: add API to get a BAR's mapped address Avi Kivity
2011-06-27 13:22 ` [Qemu-devel] [RFC v2 14/20] vmsvga: don't remember pci BAR address in callback any more Avi Kivity
2011-06-27 13:22 ` [Qemu-devel] [RFC v2 15/20] vga: convert vga and its derivatives to the memory API Avi Kivity
2011-06-27 13:22 ` [Qemu-devel] [RFC v2 16/20] cirrus: simplify mmio BAR access functions Avi Kivity
2011-06-27 13:22 ` [Qemu-devel] [RFC v2 17/20] cirrus: simplify bitblt " Avi Kivity
2011-06-27 13:22 ` [Qemu-devel] [RFC v2 18/20] cirrus: simplify vga window mmio " Avi Kivity
2011-06-27 13:22 ` [Qemu-devel] [RFC v2 19/20] vga: " Avi Kivity
2011-06-27 13:22 ` [Qemu-devel] [RFC v2 20/20] cirrus: simplify linear framebuffer " Avi Kivity
2011-06-27 15:13 ` [Qemu-devel] [RFC v2 00/20] Memory API Avi Kivity
2011-06-27 15:52 ` Michael S. Tsirkin
2011-06-27 15:54 ` Avi Kivity
2011-06-27 15:59 ` Michael S. Tsirkin
2011-06-27 16:10 ` Avi Kivity
2011-06-27 20:28 ` Anthony Liguori [this message]
2011-06-27 15:37 ` Anthony Liguori
2011-06-27 15:44 ` Avi Kivity
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