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Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected
From: |
Hans de Goede |
Subject: |
Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected |
Date: |
Fri, 22 Mar 2013 09:58:20 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 |
Hi,
On 03/22/2013 09:25 AM, Gerd Hoffmann wrote:
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.
Thanks for the above overview, very useful!
(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.
I've to nack this one, spicevmc is a chardev backend which is also used
with other frontends then just virtio-console, atm it is also used together
with the usb-redir and smartcard frontends and there is no reason why it
could not be used with others in the future, so: NACK.
Regards,
Hans
- [Qemu-devel] [PATCH v3 0/2] spice-qemu-char fix agent mouse after migration, (continued)
- [Qemu-devel] [PATCH v3 0/2] spice-qemu-char fix agent mouse after migration, Alon Levy, 2013/03/21
- [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Alon Levy, 2013/03/21
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Anthony Liguori, 2013/03/21
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Alon Levy, 2013/03/21
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Anthony Liguori, 2013/03/21
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Alon Levy, 2013/03/21
- Re: [Qemu-devel] [PATCH 1/2] char: add qemu_chr_be_is_fe_connected, Alon Levy, 2013/03/21
- 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 <=
- 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