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I need to retrieve config file from guest VM without network support. The simplest way to do that is probably to use serial port. As far as I understand I need to create kind of serial port "loop" so that I'll connect using eg. minicom to lets say /dev/vttyS0 and I'll assign /dev/vttyS1 to VirtualBox guest.
Guest is using baud rate 115200. How do I create such pair of devices?
I tried socat:
socat -d -d pty,raw,echo=0 pty,raw,echo=0
However VirtualBox doesn't seem to understand it as correct serial device throwing error
Ioctl failed for serial host device /dev/pts/10 (VERR_INVALID_PARAMETER)
Device will not work properly
ErrorID DrvHostSerialFail
Severity Warning
Installing Guest additions, so you can mount a shared storage into both Guest and Host, is out of the question? – Marek Rost – 2017-06-29T05:34:19.697
@MarekRost it's proprietary embedded OS. Doesn't have standard prompt nor even direct access to drive. It only has configuration prompt with command that dumps device configuration to console output. It seems to be the only way to get config out of device. It doesn't even support framebuffer, VirtualBox is displaying standard VM monitor using serial port 0. – Lapsio – 2017-06-29T20:07:00.960