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    SubjectRe: earlycon: no match?
    On Thu, May 07, 2015 at 01:22:11PM -0400, Peter Hurley wrote:
    > On 05/07/2015 01:09 PM, Maciej W. Rozycki wrote:
    > > On Mon, 4 May 2015, Peter Hurley wrote:
    > >
    > >>>> Since 2007, 'console=' is a early param synonym for 'earlycon='; IOW,
    > >>>> the message is new but not the behavior.
    > >>>
    > >>> "console=" had nothing to do with early param before.
    > >>
    > >> *Yes, it has* since the commit I referenced in the previous email and
    > >> the email before that when I noted that 'console=' and 'earlycon=' are
    > >> synonyms if CONFIG_SERIAL_EARLYCON=y, and it has been that way since
    > >> 2007.
    > >>
    > >> The only thing that has changed is that I added a diagnostic; _to repeat_,
    > >> the earlycon matching code has always run in this case, only the
    > >> diagnostic is new.
    > >
    > > What's the point of having two parameters as synonyms whose syntax is not
    > > compatible to each other in the general case? I'd expect the following
    > > cases to be handled:
    > >
    > > 1. Regular console only (no early console requested) => `console=foo...'.
    > >
    > > 2. Both early and regular console => `earlycon=blah... console=foo...'.
    > >
    > > 3. Early console handing over to regular console => `earlycon=blah...'.
    >
    > 4. Early console only => `earlycon=blah...'
    >
    > How to distinguish between 3 & 4?

    Given that the aliasing only makes sense for console=uart, and
    console=uart8250, we can do the following. Not exactly the nicest
    code, but only slighty more ugly than what we have now in
    do_early_param()

    Sascha

    --------------------------8<----------------------------

    From e4d5a09877e48308ee0cf4170f2eef8aa2f747f5 Mon Sep 17 00:00:00 2001
    From: Sascha Hauer <s.hauer@pengutronix.de>
    Date: Fri, 8 May 2015 08:23:47 +0200
    Subject: [PATCH] param: console: Do not treat console as synonym for earlycon

    Since 2007 console= and earlycon= are treated as synonyms, but the
    syntax for both options is different. The only case in which they
    are identical is for console=uart or console=uart8250. All other
    cases currently lead to the warning:

    earlycon: no match for xxx

    This patch drops the general aliasing, but keeps the current
    behaviour for console=uart and console=uart8250 to keep the kernel
    parameters compatible.

    Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
    ---
    init/main.c | 9 ++++++---
    1 file changed, 6 insertions(+), 3 deletions(-)

    diff --git a/init/main.c b/init/main.c
    index 2115055..bfcbbc5 100644
    --- a/init/main.c
    +++ b/init/main.c
    @@ -413,12 +413,15 @@ static noinline void __init_refok rest_init(void)
    static int __init do_early_param(char *param, char *val, const char *unused)
    {
    const struct obs_kernel_param *p;
    + bool earlyconalias = false;
    +
    + if (val && !strcmp(param, "console") &&
    + (!strncmp(val, "uart,", 5) || !strncmp(val, "uart8250,", 9)))
    + earlyconalias = true;

    for (p = __setup_start; p < __setup_end; p++) {
    if ((p->early && parameq(param, p->str)) ||
    - (strcmp(param, "console") == 0 &&
    - strcmp(p->str, "earlycon") == 0)
    - ) {
    + (earlyconalias && strcmp(p->str, "earlycon") == 0)) {
    if (p->setup_func(val) != 0)
    pr_warn("Malformed early option '%s'\n", param);
    }
    --
    2.1.4
    --
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