KVM: 0.163 device: 0.149 semantic: 0.108 other: 0.108 files: 0.091 vnc: 0.071 performance: 0.050 boot: 0.049 graphic: 0.041 network: 0.038 socket: 0.036 PID: 0.035 debug: 0.035 permissions: 0.026 KVM: 0.555 debug: 0.105 network: 0.096 socket: 0.036 performance: 0.034 other: 0.032 files: 0.032 PID: 0.029 device: 0.029 semantic: 0.015 boot: 0.012 vnc: 0.011 graphic: 0.008 permissions: 0.008 data sent to serial interface gets truncated after 64kb When sending more than 64kb of data to the serial interface in a short timespan, the data seems to disappear. I tested it with the latest release (qemu-kvm-1.2.0-rc2.tar.gz) where the bug still occurs. I stumbled upon it when I upraged my qemu version. The bug did not occur in the last version i had (0.12.5). You can reproduce it as follows: 1. Start a dd or cat command in one terminal and pipe the output to a netcat. The testfile has to be larger than 64kb. I used one that had 93kb and did contain only ascii text. $ dd if= | nc -l 127.0.0.1 65432 or $ cat | nc -l 127.0.0.1 65432 2. Start a qemu and let the first serial port connect to the listening netcat. I suppose that the testsystem can be any system that does not read from the serial port on its own (e.g. during boot process). I used a self compiled minimal linux. $ qemu -cdrom -serial tcp:127.0.0.1:65432 3. When the testsystem is booted, read from the serial device and write it to a file. $ dd if=/dev/ttyS0 of=/tmp/testFile or $ cat /dev/ttyS0 > /tmp/testFile The result in almost all of my testruns is, that the /tmp/testFile does only has the size of 64kb. The rest of the data vanished. In some cases the file was slightly bigger (65kb or 67kb) but allways under 70kb. The complete file (93kb) was not trasmitted in any of the runs. I hope my explanation is exactly enough for you to reproduce it. Triaging old bug tickets ... can you still reproduce this issue with the latest version of QEMU (version 2.9)? [Expired for QEMU because there has been no activity for 60 days.]