Messages in this thread | | | Date | Tue, 17 Jul 2018 16:48:54 -0400 (EDT) | From | Nicolas Pitre <> | Subject | Re: [PATCH] ARM: early_printk: respect keep parameter |
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On Tue, 17 Jul 2018, Alexandre Belloni wrote:
> On 17/07/2018 16:16:44-0400, Nicolas Pitre wrote: > > On Wed, 11 Jul 2018, Alexandre Belloni wrote: > > > > > Parse and use the keep parameter of earlyprintk to avoid having the kernel > > > output stop with: > > > > > > Console: colour dummy device 80x30 > > > console [tty0] enabled > > > bootconsole [earlycon0] disabled > > > > > > This happens because once tty0, the virtual terminal console is registered, > > > it is selected as the default console, disregarding an existing stdout-path > > > DT property and the early console is shutdown before the console driver is > > > probed. > > > > > > Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> > > > > Why can't you have a real console driver that takes over at that point > > which respects whatever DT property you give it? > > > > See Russell's analysis here: > > https://www.spinics.net/lists/linux-serial/msg25363.html
That is a good analysis, but not necessarily a good argument for this particular patch.
> > The early_printk code is very raw and inefficient, and it shouldn't be > > used for anything but the debugging of early boot hangs. > > > > The issue I had is that he pinctrl driver wasn't probing so the real > console driver could never probe. I think this fits the use case.
Yes, that certainly fits. This is not what your commit log message is saying though.
> Also, atmel_serial doesn't yet have earlycon support.
Fair enough, and probably something you should mention too.
> > > --- > > > arch/arm/kernel/early_printk.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/arch/arm/kernel/early_printk.c b/arch/arm/kernel/early_printk.c > > > index 9257736ec9fa..bbb10150b11a 100644 > > > --- a/arch/arm/kernel/early_printk.c > > > +++ b/arch/arm/kernel/early_printk.c > > > @@ -42,6 +42,9 @@ static struct console early_console_dev = { > > > > > > static int __init setup_early_printk(char *buf) > > > { > > > + if (buf && strstr(buf, "keep")) > > > + early_console_dev.flags &= ~CON_BOOT; > > > + > > > early_console = &early_console_dev; > > > register_console(&early_console_dev); > > > return 0; > > > -- > > > 2.18.0 > > > > > > > > > > -- > Alexandre Belloni, Bootlin (formerly Free Electrons) > Embedded Linux and Kernel engineering > https://bootlin.com >
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