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I have a headless appliance that has a lone serial console. I have an external HD with Linux installed. I can boot linux on my appliance using the USB HD (I know this because I can log into the router and see that there is an IP for the appliance and the OS name is displayed). The console (through Putty) displays everything up until the following lines, then there is nothing:

Loading /live/vmlinuz... ok
Loading /live/initrd.img...ok

Does anyone have any ideas? On bios, the proper baud rate is set to 115200 and I have that set correctly. Can anyone help me out here? It's a headless system, so it's a little tricky.

Thanks!

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You'll need to specify a boot option to tell the kernel to send its normal console output to a serial port. It looks like your device is redirecting BIOS text-mode output to the serial port until the Linux kernel takes over, so you might be able to communicate with the bootloader as-is.

If the serial port is the default PC-style COM1:, i.e. it has I/O address 0x3f8 and IRQ 4, the boot option you need is console=ttyS0,115200n8. If the serial port is more special than that, youo may need another TTY device name and/or more options: for example, ARM devices might use ttySA0 or ttyAM0.

If your OEL/RHEL distribution is version 6.0 or greater, this is all you need to do: in 7.x, systemd is configured to automatically provide a login prompt (a getty process) to any serial port mentioned in the console= boot options. OEL/RHEL 6.x versions do the same using upstart.

For OEL/RHEL 5.x, you definitely had to configure a getty for a serial console in /etc/inittab in the classic SysVinit style in addition to the kernel console= option.

  • You're a beast. Works for OEL 6. Thanks! – jonesy19 May 13 '18 at 22:13

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