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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Thu, 23 Jun 2022 12:10:00 +0200
Message-ID: <CAMuHMdV7trsRg0x9w8ZfHp0UHZ8PE+EoddAzf9nmtjGrO4YfPw@mail.gmail.com>
Subject: Re: [PATCH printk v5 1/1] printk: extend console_lock for per-console locking
To:     John Ogness <john.ogness@linutronix.de>
Cc:     Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-riscv <linux-riscv@lists.infradead.org>
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Hi John,

On Thu, Jun 23, 2022 at 12:37 AM John Ogness <john.ogness@linutronix.de> wrote:
> On 2022-06-22, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > I have bisected another intriguing issue to this commit: on SiPEED
> > MAiX BiT (Canaan K210 riscv), it no longer prints the line detecting
> > ttySIF0, i.e. the console output changes like:
> >
> >      spi-nor spi1.0: gd25lq128d (16384 Kbytes)
> >      i2c_dev: i2c /dev entries driver
> >      k210-fpioa 502b0000.pinmux: K210 FPIOA pin controller
> >     -38000000.serial: ttySIF0 at MMIO 0x38000000 (irq = 1, base_baud =
> > 115200) is a SiFive UART v0
> >      printk: console [ttySIF0] enabled
> >      printk: bootconsole [sifive0] disabled
> >      printk: console [ttySIF0] printing thread started
> >
> > As this patch does not make any changes to drivers/tty/, and ttySIF0
> > does work (it's the console), I looked in /proc/kmsg, and bingo,
> > the missing line is there, so it is generated, but never printed.
>
> What is sifive0? Are you using the earlycon driver to create an early
> boot console? Can I see your boot args?

earlycon: sifive0 at MMIO 0x0000000038000000 (options '115200n8')
printk: bootconsole [sifive0] enabled
Kernel command line: earlycon console=ttySIF0 rootdelay=2 root=/dev/mmcblk0p1 ro

> There is a known issue the that earlycon does not synchronize with
> normal consoles. A patch was recently posted [0] on LKML.

> [0] https://lore.kernel.org/lkml/20220621090900.GB7891@pathway.suse.cz

Thank you, that did the trick!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds