Yes, this is very usefull. Personally I was done for my custom archiso. Not only touching /etc/inittab and /etc/securetty also for menu.lst for grub and syslinux.

* for grub adding these lines and duplicating entries for kernel adding console="ttyS0":
serial --unit=0 --speed=9600
terminal --timeout=3 console serial

in this way grub prompts 3 times (to continue) in both serial port and console, if not entry then show menu in normal console.
For syslinux only adding "serial 0 9600" as the first line in isolinux.cfg (and both duplicated entries for kernel with console="ttyS0".

The issue here is making this more generic :) other serial port than COM1 for real hardware. For virtual enviroments there are no issue (as far I know).

gerardo what exactly do you mean with "Not only touching /etc/inittab and /etc/securetty " ?
you have to modify inittab, securetty *and* grub/syslinux ?

what are all needed changes to all files in order to make this is as good as possible without bothering "normal" users? and would that be good enough?

changes in /etc/securetty + /etc/inittab + isolinux.cfg + a script that is launched from init. This script must detect if console=ttyS0 then launch agetty, otherwise should keep in a infinite loop that does nothing.

Also can cover ttyUSB* devices.

Patch sent http://mailman.archlinux.org/pipermail/arch-releng/2011-March/001536.html
This is half of it anyway. Makes agetty start on the first kernel console.

Second part is a bit more difficult since it's bootloader configuration. There's a couple common cases:
* If you're doing PXE booting or something you're probably going to just edit the bootloader config yourself anyway.
* If you're booting off a usb stick or cdrom and all you have available is a serial port, the best we could do is add a "serial 0 38400" line in the bootloader config, which would let you operate the bootloader (and thus console= and so on) from ttyS0. Probably covers most of these cases where virtualization or physical access are involved.

Simo, if we add the "serial 0 38400" line to the bootloader, could that hurt other users who do not want this?
Otherwise, let's just do it, if it makes everyone happy.

http://mailman.archlinux.org/pipermail/arch-releng/2011-March/001541.html

I think it should be ok. I tried it in a VM without any serial hardware exposed and it didn't complain. You might want to try it too just to make sure.

Using the March 23 ISO, this didn't work for me. The last thing i see is:

:: Starting agetty on console: ttyS0 [BUSY] [DONE]
INIT: Id "z0" respawning too fast: disabled for 5 minutes

Without having time just yet to test it, i wonder if changing the line in configs/syslinux-iso/overlay/etc/rc.d/archiso:

echo "s0:2345:respawn:/sbin/agetty ${rts} ${baud} ${dev} linux" >> /etc/inittab

to:

echo "s0:2345:respawn:/sbin/agetty ${rts} ${baud} ${dev} vt100-nav" >> /etc/inittab

will fix this?

Fixed current implementation.

Should be available in 2011.08.16 testisos.

http://projects.archlinux.org/archiso.git/commit/?id=708ba38c206a2147fbd7a357d6ece8881807231d