On Thu, 28 Sep 2017 14:18:25 +0200 Peter Zijlstra <[email protected]> wrote:
> Add add the 'force_early_printk' kernel parameter to override printk() > and force it into early_printk(). This bypasses all the cruft and fail > from printk() and makes things work again. Probably break this up into two patches. One for creation of early_vprintk(), and the other to add the force_early_printk parameter. -- Steve > > Signed-off-by: Peter Zijlstra (Intel) <[email protected]> > --- > kernel/printk/printk.c | 68 > +++++++++++++++++++++++++++++++++---------------- > 1 file changed, 47 insertions(+), 21 deletions(-) > > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -365,6 +365,42 @@ __packed __aligned(4) > #endif > ; > > +#ifdef CONFIG_EARLY_PRINTK > +struct console *early_console; > + > +static bool __read_mostly force_early_printk; > + > +static int __init force_early_printk_setup(char *str) > +{ > + force_early_printk = true; > + return 0; > +} > +early_param("force_early_printk", force_early_printk_setup); > + > +static int early_vprintk(const char *fmt, va_list args) > +{ > + char buf[512]; > + int n; > + > + n = vscnprintf(buf, sizeof(buf), fmt, args); > + early_console->write(early_console, buf, n); > + > + return n; > +} > + > +asmlinkage __visible void early_printk(const char *fmt, ...) > +{ > + va_list ap; > + > + if (!early_console) > + return; > + > + va_start(ap, fmt); > + early_vprintk(fmt, ap); > + va_end(ap); > +} > +#endif > + > /* > * The logbuf_lock protects kmsg buffer, indices, counters. This can be > taken > * within the scheduler's rq lock. It must be released before calling > @@ -1816,6 +1852,11 @@ asmlinkage int vprintk_emit(int facility > return vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); > #endif > > +#ifdef CONFIG_EARLY_PRINTK > + if (force_early_printk && early_console) > + return early_vprintk(fmt, args); > +#endif > + > if (level == LOGLEVEL_SCHED) { > level = LOGLEVEL_DEFAULT; > in_sched = true; > @@ -1939,7 +1980,12 @@ asmlinkage __visible int printk(const ch > int r; > > va_start(args, fmt); > - r = vprintk_func(fmt, args); > +#ifdef CONFIG_EARLY_PRINTK > + if (force_early_printk && early_console) > + r = vprintk_default(fmt, args); > + else > +#endif > + r = vprintk_func(fmt, args); > va_end(args); > > return r; > @@ -1975,26 +2021,6 @@ static size_t msg_print_text(const struc > static bool suppress_message_printing(int level) { return false; } > #endif /* CONFIG_PRINTK */ > > -#ifdef CONFIG_EARLY_PRINTK > -struct console *early_console; > - > -asmlinkage __visible void early_printk(const char *fmt, ...) > -{ > - va_list ap; > - char buf[512]; > - int n; > - > - if (!early_console) > - return; > - > - va_start(ap, fmt); > - n = vscnprintf(buf, sizeof(buf), fmt, ap); > - va_end(ap); > - > - early_console->write(early_console, buf, n); > -} > -#endif > - > static int __add_preferred_console(char *name, int idx, char *options, > char *brl_options) > { >
