Why does qemu guest turn on the Host serial device post-processing options?
Issue
On the Host, even using -opost
, which tells to your serial port to ignore any enabled specific post-processing option:
[root@host ~]# stty -F /dev/ttyS4 -opost
If a qemu Guest inside the Host tries to transmit data using a virtual serial port mapped to the physical serial ttyS4
, the data transmitted will be affected by post-processing options.
For example, in a given qemu Guest with /dev/ttyS0
mapped to Host /dev/ttyS4
, writing the following characters on guest serial device /dev/ttyS0
:
0x41
0x0A
0x42
The data captured from Host serial device /dev/ttyS4
will be:
0x41
0x0D
0x0A
0x42
In this case, the data is affected by onlcr
post-processing option, translating newline (0x0A
) to carriage return-newline (0x0D
).
Environment
- Red Hat Enterprise Linux 6
- qemu-kvm-0.12
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