[Qemu-commits] [qemu/qemu] bce626: virtio-console: set frontend open permanently for ...

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/qemu/qemu
  Commit: bce6261eb2d879625126485d4ddd28cacb93152e
      
https://github.com/qemu/qemu/commit/bce6261eb2d879625126485d4ddd28cacb93152e
  Author: Daniel P. Berrange <address@hidden>
  Date:   2016-08-11 (Thu, 11 Aug 2016)

  Changed paths:
    M hw/char/virtio-console.c

  Log Message:
  -----------
  virtio-console: set frontend open permanently for console devs

The virtio-console.c file handles both serial consoles
and interactive consoles, since they're backed by the
same device model.

Since serial devices are expected to be reliable and
need to notify the guest when the backend is opened
or closed, the virtio-console.c file wires up support
for chardev events. This affects both serial consoles
and interactive consoles, using a network connection
based chardev backend such as 'socket', but not when
using a PTY based backend or plain 'file' backends.

When the host side is not connected the handle_output()
method in virtio-serial-bus.c will drop any data sent
by the guest, before it even reaches the virtio-console.c
code. This means that if the chardev has a logfile
configured, the data will never get logged.

Consider for example, configuring a x86_64 guest with a
plain UART serial port

  -chardev 
socket,id=charserial1,host=127.0.0.1,port=9001,server,nowait,logfile=console1.log,logappend=on
  -device isa-serial,chardev=charserial1,id=serial1

vs a s390 guest which has to use the virtio-console port

  -chardev 
socket,id=charconsole1,host=127.0.0.1,port=9000,server,nowait,logfile=console2.log,logappend=on
  -device virtconsole,chardev=charconsole1,id=console1

The isa-serial one gets data written to the log regardless
of whether a client is connected, while the virtioconsole
one only gets data written to the log when a client is
connected.

There is no need for virtio-serial-bus.c to aggressively
drop the data for console devices, as the chardev code is
prefectly capable of discarding the data itself.

So this patch changes virtconsole devices so that they
are always marked as having the host side open. This
ensures that the guest OS will always send any data it
has (Linux virtio-console hvc driver actually ignores
the host open state and sends data regardless, but we
should not rely on that), and also prevents the
virtio-serial-bus code prematurely discarding data.

The behaviour of virtserialport devices is *not* changed,
only virtconsole, because for the former, it is important
that the guest OSknow exactly when the host side is opened
/ closed so it can do any protocol re-negotiation that may
be required.

Fixes bug: https://bugs.launchpad.net/qemu/+bug/1599214

Acked-by: Cornelia Huck <address@hidden>
Signed-off-by: Daniel P. Berrange <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Amit Shah <address@hidden>


  Commit: bea048dcb936816627301cb1744624eb79ac0488
      
https://github.com/qemu/qemu/commit/bea048dcb936816627301cb1744624eb79ac0488
  Author: Peter Maydell <address@hidden>
  Date:   2016-08-11 (Thu, 11 Aug 2016)

  Changed paths:
    M hw/char/virtio-console.c

  Log Message:
  -----------
  Merge remote-tracking branch 'remotes/amit/tags/vser-for-2.7-1' into staging

virtio-console: fix receiving data from guest

# gpg: Signature made Thu 11 Aug 2016 12:17:55 BST
# gpg:                using RSA key 0xEB0B4DFC657EF670
# gpg: Good signature from "Amit Shah <address@hidden>"
# gpg:                 aka "Amit Shah <address@hidden>"
# gpg:                 aka "Amit Shah <address@hidden>"
# Primary key fingerprint: 48CA 3722 5FE7 F4A8 B337  2735 1E9A 3B5F 8540 83B6
#      Subkey fingerprint: CC63 D332 AB8F 4617 4529  6534 EB0B 4DFC 657E F670

* remotes/amit/tags/vser-for-2.7-1:
  virtio-console: set frontend open permanently for console devs

Signed-off-by: Peter Maydell <address@hidden>


Compare: https://github.com/qemu/qemu/compare/144a6db0b0eb...bea048dcb936