= User Serial Console =

In order to use a serial console for the command line UI, a couple of conditions have to be met:

  * HelenOS must support passing boot arguments to the kernel on the given platform
  * HelenOS must have a userspace driver for the serial console device
  * the user needs to pass the exact location service path to the serial console device in the `console` argument

Currently, these requirements are satisfied on ia32, amd64 and sparc64/sun4u.

== ia32 and amd64 ==

Assuming your serial console device is at `devices/\hw\pci0\00:01.0\com1\a` (this is the case in QEMU), modify your grub.cfg to contain the following:

{{{
	multiboot /boot/kernel.bin console=devices/\\hw\\sys\\00:01.0\\com1\\a
}}}

Note that the backslashes must be escaped on the GRUB command line. If you are modifying boot/Makefile.grub, make sure to escape the backslashes properly:

{{{
=== modified file 'boot/Makefile.grub'
--- boot/Makefile.grub	2016-04-05 19:04:11 +0000
+++ boot/Makefile.grub	2017-05-06 13:38:00 +0000
@@ -85,7 +85,7 @@
 	for module in $(MODULES) ; do \
 		echo "	echo 'Loading $$module'" >> $(BOOT_CONFIG) ; \
 		if [ "$$module" = "kernel.bin" ] ; then \
-			echo "	$(MULTIBOOT_CMD) /boot/$$module" >> $(BOOT_CONFIG) ; \
+			echo "	$(MULTIBOOT_CMD) /boot/$$module console=devices/\\\\hw\\\\sys\\\\00:01.0\\\\com1\\\\a" >> $(BOOT_CONFIG) ; \
 		else \
 			echo "	$(MODULE_CMD) /boot/$$module /boot/$$module" >> $(BOOT_CONFIG) ; \
 		fi \

}}}

Upon boot, the `console` service should start using the serial console for its input/output. We can run HelenOS using the `tools/ew.py` in QEMU:

{{{
$ xterm -e `tools/ew.py -d` -serial stdio
}}}

or if we want a complete headless run, we do:

{{{
xterm -e `tools/ew.py -d` -nographic
}}}

== sparc64/sun4u ==

Serial console on sun4u is known to be working only under QEMU and is fully integrated into `tools\ew.py`:

{{{
bash-4.3$ tools/ew.py -d
xterm -T "HelenOS/sparc64 on generic" -e qemu-system-sparc64 -M sun4u --prom-env boot-args="console=devices/\hw\pci0\00:03.0\com1\a" -drive file=hdisk.img,index=0,media=disk,format=raw -device e1000,vlan=0 -net user,hostfwd=udp::8080-:8080,hostfwd=udp::8081-:8081,hostfwd=tcp::8080-:8080,hostfwd=tcp::8081-:8081,hostfwd=tcp::2223-:2223 -usb -boot d -cdrom image.iso -nographic
}}}