Comment 16 for bug 682831

Oh, one more note, it seems that
drivers/xen/console/console.c:
# * Modes:
# * 'xencons=off' [XC_OFF]: Console is disabled.
# * 'xencons=tty' [XC_TTY]: Console attached to '/dev/tty[0-9]+'.
# * 'xencons=ttyS' [XC_SERIAL]: Console attached to '/dev/ttyS[0-9]+'.
# * 'xencons=xvc' [XC_XVC]: Console attached to '/dev/xvc0'.
# * 'xencons=hvc' [XC_HVC]: Console attached to '/dev/hvc0'.
# * default: XC_XVC

'default' seems incorrect. I see:
static enum {
   XC_OFF, XC_TTY, XC_SERIAL, XC_XVC, XC_HVC
} xc_mode;
static int xc_num = -1;
...
void xencons_early_setup(void)
{
    if (is_initial_xendomain()) {
        xc_mode = XC_SERIAL;
    } else {
        xc_mode = XC_TTY;
        console_use_vt = 0;
    }
}

That is more in line with what I'm seeing, where XC_TTY would cause the default behavior for xencons to be tty1.