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Re: [Qemu-devel] [RFC] Memory API
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [RFC] Memory API |
Date: |
Wed, 18 May 2011 19:40:20 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2011-05-18 19:15, Avi Kivity wrote:
> On 05/18/2011 08:07 PM, Jan Kiszka wrote:
>> On 2011-05-18 18:47, Avi Kivity wrote:
>>>>>> I'm specifically thinking of fully trackable slot updates. The clients
>>>>>> should not have to maintain the flat layout. They should just receive
>>>>>> updates in the form of slot X added/modified/removed. For now, this
>>>>>> magic happens multiple times in the clients, and that is very bad.
>>>>>
>>>>> Slots don't have any meaning. You can have a RAM region which is
>>>>> overlaid by a smaller mmio region -> the RAM slot is split into two.
>>>>>
>>>>> We should just send clients a list of ranges, and they can associate
>>>>> them with slots themselves.
>>>>
>>>> And that association logic should be as simple as matching a unique
>>>> range ID against an existing slot (for updates and deletions) or adding
>>>> a new slot for a new range and storing the ID. Anything else will not
>>>> allow to simplify the existing code bases noticeably. That's my point.
>>>
>>> We won't have a natural ID.
>>
>> The address of the data structure describing a region could be such a
>> thing. Provided, of course, we prepare a flatted view ahead of time, not
>> on the fly.
>
> It will change as soon as the memory map changes.
...which is supposed to be properly reported to the client beforehand.
>
>>> But I'll see if I can have a library
>>> calculate the minimum difference between the previous layout and current
>>> layout. Should not be too hard.
>>
>> We need exact match on the client side with the old range. E.g. if you
>> put a new region over an existing one, effectively splitting it into two
>> halves, the core has to
>> - shrink the existing range to form the first half
>> - register two new ranges to reflect the rest
>>
>> On unregistering of that overlap, we need the reverse. So all the client
>> has to do then is to decide if it is interested in some range, and then
>> store it internally with some additional data (and process it, of
>> course). No more merging, no more overlap detection and splitting up at
>> client level.
>
> Right. We do a symmetric set difference between the old and new maps
> and let the client know what has changed.
That would be fine as well. Then the internal representation could be
anything, though I bet a flattened form would have its advantages.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
- Re: [Qemu-devel] [RFC] Memory API, (continued)
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API,
Jan Kiszka <=
- Re: [Qemu-devel] [RFC] Memory API, Richard Henderson, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Gleb Natapov, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Gleb Natapov, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Gleb Natapov, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Gleb Natapov, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19