[Qemu-devel] Serial telnet console drops incoming characters on git master

[Mark Cave-Ayland]

Hi Daniel,

I found another issue where the latest set of console updates appear to
break -serial telnet on qemu-system-sparc. What I see is that while
incoming serial telnet appears fine, outgoing serial telnet traffic
caused by typing over the serial connection results in every other
character being dropped.

A quick session with git bisect points to the following commit:

commit f2001a7e0555b66d6db25a3ff1801540814045bb
Author: Daniel P. Berrange <address@hidden>
Date:   Tue Jan 19 11:14:30 2016 +0000

    char: don't assume telnet initialization will not block

    The current code for doing telnet initialization is writing to
    a socket without checking the return status. While it is highly
    unlikely to be a problem when writing to a bare socket, as the
    buffers are large enough to prevent blocking, this cannot be
    assumed safe with TLS sockets. So write the telnet initialization
    code into a memory buffer and then use an I/O watch to fully
    send the data.

    Signed-off-by: Daniel P. Berrange <address@hidden>
    Message-Id: <address@hidden>
    Signed-off-by: Paolo Bonzini <address@hidden>

I can reproduce this with git master as follows (built on Debian Wheezy
x86-64):

'./configure' '--target-list=sparc-softmmu' --enable-trace-backends=stderr
make install

Next download a copy of the SS-20 PROM from
http://home.earthlink.net/~reif/ss20_v2.25_rom and then start QEMU with
the command line below:

./qemu-system-sparc -bios ./ss20_v2.25_rom -M SS-20 -nographic -boot c
-serial telnet:0.0.0.0:3000,server -cpu "TI SuperSparc 60" -m 64

Now telnet to port 3000 and wait for the PROM to boot all the way to the
"ok" prompt. At this point if you type over the telnet connection, you
should see that every alternate character typed is being lost.


ATB,

Mark.