[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SM
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI |
Date: |
Mon, 28 Nov 2016 11:22:06 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.0 |
On 11/28/16 10:01, Gerd Hoffmann wrote:
> Hi,
>
>> If I understand correctly, one argument against the current state of
>> writeable fw_cfg, captured in
>> <https://www.mail-archive.com/address@hidden/msg354983.html>, is
>> that callbacks on write are not supported. Apparently, QEMU code that
>> uses the data written by the guest is supposed to just read that data,
>> not to expect a notification about it.
>>
>> I'm unsure how this can work for actual negotiation, where the guest
>> usually does a read/write/read cycle, and expects some kind of change
>> between steps #2 and #3. I don't see how that can be implemented in QEMU
>> without write callbacks (i.e. how QEMU can confirm or reject the
>> negotiation attempt).
>
> Do you actually need negotiation? I think you only need to know
> whenever broadcast-smi is supported, and the presence of the
> etc/broadcast-smi (or however we name that) fw_cfg file indicates that.
Michael suggested to use negotiation like virtio does (where the host
can reject invalid combinations of requested features):
http://lists.nongnu.org/archive/html/qemu-devel/2016-11/msg03077.html
http://lists.nongnu.org/archive/html/qemu-devel/2016-11/msg03218.html
I thought negotiation was overkill:
http://lists.nongnu.org/archive/html/qemu-devel/2016-11/msg03123.html
but I figured I'd just stick with the recommendation.
> If it is there just write true/false to it to enable/disable, and qemu
> checks the field each time a smi is raised.
If we agree there's no need for negotiation, I'm game.
Thanks
Laszlo
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, (continued)
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Paolo Bonzini, 2016/11/23
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Laszlo Ersek, 2016/11/23
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Laszlo Ersek, 2016/11/23
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Kevin O'Connor, 2016/11/23
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Michael S. Tsirkin, 2016/11/23
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Laszlo Ersek, 2016/11/24
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Michael S. Tsirkin, 2016/11/24
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Laszlo Ersek, 2016/11/25
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Laszlo Ersek, 2016/11/25
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Gerd Hoffmann, 2016/11/28
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI,
Laszlo Ersek <=
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Paolo Bonzini, 2016/11/28
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Igor Mammedov, 2016/11/25
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Igor Mammedov, 2016/11/24
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Paolo Bonzini, 2016/11/24
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Igor Mammedov, 2016/11/24
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Paolo Bonzini, 2016/11/25
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Igor Mammedov, 2016/11/25
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Paolo Bonzini, 2016/11/28
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Igor Mammedov, 2016/11/28
- Re: [Qemu-devel] [PATCH v3 for-2.9 0/3] q35: add negotiable broadcast SMI, Paolo Bonzini, 2016/11/28