On Thu, Oct 2, 2014 at 2:22 PM, jonsmirl at gmail.com [off-list ref] wrote:

1) temporary early boot console -- this is nothing but an address in
RAM and the x/y layout. The character set from framebuffer is built
into the kernel.  The parallel to this is early-printk and how it uses
the UARTs without interrupts. This console vaporizes late in the boot
process -- the same thing happens with the early printk UART driver.
EARLYPRINTK on the command line enables this.

JFYI, the early serial console can also vanish, even very early in the boot
process, before the unused clocks are disabled.
Cfr. http://marc.info/?l=linux-sh&m=141227657322649&w=2

So there's no safety in this world without calling clk_prepare_enable().

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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