Re: [PATCH] Enable console on PCI serial devices

[Yinghai Lu <yinghai@kernel.org>]

n0ano@n0ano.com wrote:
> On Thu, Oct 16, 2008 at 09:23:39AM -0700, Yinghai Lu wrote:
>> ... 
>> earlycon= and conole= share uart[8250]...
>>
>> the difference console= will start from early console and switch normal console automatically if the ttyS come out with same io/mmio address etc.
>>
> 
> But there is no advantage to `earlycon' given that you can accomplish
> the same thing with `console'.  The only use that I can see is if
> you specify `earlycon' without specifying `console' and then all
> you get are the initial kernel messages, after the serial drivers
> intializes all further messages go to the VGA.  If makes much more
> sense to me to just use the `console' parameter to get all kernel
> messages on the serial port, and then there is no need for
> `earlycon'.
> 


/* Check for early params. */
static int __init do_early_param(char *param, char *val)
{
        struct obs_kernel_param *p;

        for (p = __setup_start; p < __setup_end; p++) {
                if ((p->early && strcmp(param, p->str) == 0) ||
                    (strcmp(param, "console") == 0 &&
                     strcmp(p->str, "earlycon") == 0)
                ) {
                        if (p->setup_func(val) != 0)
                                printk(KERN_WARNING
                                       "Malformed early option '%s'\n", param);
                }
        }
        /* We accept everything at this stage. */
        return 0;
}

we need that holder in console sections to compare with console and earlycon.

YH