I am also seeing this problem. In case it was not clear from Paul's original report, it affects guests using a serial console.
Also, it is not specific to NetBSD. I can reproduce it using a Linux guest on a Linux host, by running the following on a Debian 8 system: wget http://landley.net/aboriginal/downloads/old/binaries/1.4.5/system-image-i686.tar.gz tar xfz system-image-i686.tar.gz cd system-image-i686 sh run-emulator.sh and typing Control-A b m once the guest has started. Using qemu 2.1.2, this successfully causes the guest to print a memory usage summary. Using current qemu sources from git (dbe2b65566e76d3c3a0c3358285c0336ac61e757), nothing happens. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1654137 Title: Ctrl-A b not working in 2.8.0 Status in QEMU: New Bug description: With a recent update from 2.7.0 to 2.8.0 I have discovered that I can no longer send a "break" to the VM. Ctrl-A b is simply ignored. Other Ctrl-A sequences seem to work correctly. This is on a NetBSD amd64 system, version 7.99.53, and qemu was installed on this system from source. Reverting to the previous install restores "break" capability. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1654137/+subscriptions
