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Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected |
Date: |
Fri, 22 Mar 2013 09:25:48 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130307 Thunderbird/17.0.3 |
Hi,
> There isn't a notion of "connected" for the front-ends in the char
> layer. The closest thing is whether add_handlers() have been called or
> not.
It isn't new. There are qemu_chr_fe_open + qemu_chr_fe_close doing
exactly that signaling (whenever someone has opened the virtio-serial
port, i.e. whenever the guest agent is active or not).
Problem is the chardev forgets this state over migration.
So we need a way to restore the state. virtio-serial knows it of course
as this is guest state it has to keep track of it. We just need a way
the chardev can figure what the current state is after migration.
The options I see:
(1) Have chardev store the state itself in a new migration section.
This is what I've NAK'ed. First, because live-migration host
state is a can of worms I don't want open. Second because it
actually isn't host state.
(2) virtio-serial could just call qemu_chr_fe_open in
post_migration hook. Could have unwanted side effects as
the chardev can't figure whenever this is a post-load call
or a guest-open call.
(3) Add a new qemu_chr_fe_* call for virtio-serial to notify the
chardev. This was the next proposal from Alon
(4) Do it the other way around: Allow the chardev query what the
current state is. This patch series.
(5) Cut off the chardev layer altogether and implement spicevmc as
virtio-serial port. Your proposal if I understand it correctly.
Makes sense, but breaks backward compatibility, so even when
doing this we must fix the chardev spicevmc bug somehow.
Hope this clarifies,
Gerd
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, (continued)
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Hans de Goede, 2013/03/22
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Anthony Liguori, 2013/03/22
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Gerd Hoffmann, 2013/03/22
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Hans de Goede, 2013/03/22
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Anthony Liguori, 2013/03/22
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Hans de Goede, 2013/03/24
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected,
Gerd Hoffmann <=
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Hans de Goede, 2013/03/22
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Anthony Liguori, 2013/03/22
- [Qemu-devel] [PATCH 2/2] spice-qemu-char: register interface on post load, Alon Levy, 2013/03/21
- Re: [Qemu-devel] [PATCH 2/2] spice-qemu-char: register interface on post load, Hans de Goede, 2013/03/22
- Re: [Qemu-devel] [PATCH 2/2] spice-qemu-char: register interface on post load, Alon Levy, 2013/03/22
- Re: [Qemu-devel] [PATCH 2/2] spice-qemu-char: register interface on post load, Hans de Goede, 2013/03/22
[Qemu-devel] [PATCH 3/4] virtio-console: implement post_load to call to qemu_chr_fe_post_load, Alon Levy, 2013/03/20
[Qemu-devel] [PATCH 4/4] spice-qemu-char: register interface on post load, Alon Levy, 2013/03/20