[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC] Memory API
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [RFC] Memory API |
Date: |
Thu, 19 May 2011 16:06:22 +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 2011-05-19 16:04, Anthony Liguori wrote:
> On 05/19/2011 08:57 AM, Jan Kiszka wrote:
>> On 2011-05-19 15:52, Anthony Liguori wrote:
>>> On 05/19/2011 03:30 AM, Jan Kiszka wrote:
>>>> On 2011-05-19 10:26, Gleb Natapov wrote:
>>>>> On Wed, May 18, 2011 at 09:27:55PM +0200, Jan Kiszka wrote:
>>>>>>> if an I/O is to the APIC page,
>>>>>>> it's handled by the APIC
>>>>>>
>>>>>> That's not that simple. We need to tell apart:
>>>>>> - if a cpu issued the request, and which one => forward to APIC
>>>>> And cpu mode may affect where access is forwarded to. If cpu is in SMM
>>>>> mode access to frame buffer may be forwarded to a memory (depends on
>>>>> chipset configuration).
>>>>
>>>> So we have a second use case for CPU-local I/O regions?
>>>>
>>>> I wonder if only a single CPU can enter SMM or if all have to.
>>>
>>> For the i440fx, it's a chipset register (not a per-CPU register).
>>
>> There are two sources: the chipset register and the mode of the first
>> CPU. Both things were apparently incorrectly merged into the
>> minimalistic i440fx model.
>
> Right, the chipset register is mainly used to program the contents of SMM.
>
> There is a single access pin that has effectively the same semantics as
> setting the chipset register.
>
> It's not a per-CPU setting--that's the point. You can't have one CPU
> reading SMM memory at the exactly same time as accessing VGA.
>
> But I guess you can never have two simultaneous accesses anyway so
> perhaps it's splitting hairs :-)
Not sure. If one CPU enters SMM, it must be able to read SMRAM content,
independently of the second CPU - unless there is some magic to stop
that CPU in the meantime.
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, Gleb Natapov, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API,
Jan Kiszka <=
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/20
- Re: [Qemu-devel] [RFC] Memory API, Blue Swirl, 2011/05/20
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/22
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/19