Hi Sukanto,
On Sat, Jan 28, 2012 at 11:25 PM, Sukanto Ghosh
<sukanto.cse.iitb@xxxxxxxxx> wrote:
> Hi Dave,
>
> If you look into start_kernel() the call to parse_early_param()
> precedes mm_init().
> parse_early_param() eventually calls do_early_param().
> do_early_param() parses for "earlycon" in kernel commandline and then calls the
> setup_function associated with earlycon.
>
> I have in my commandline: earlycon=uart8250,mmio32,0x10000000,9600
>
> Call flow starting from drivers/tty/serial/8250_early.c will lead to kmalloc
>
> early_param("early_con", setup_early_serial8250_console)
> setup_early_serial8250_console()
> early_serial8250_setup()
> parse_options()
> ioremap_nocache()
> ... arch-specific-ioremap
> -- some form of arch specific __ioremap_caller
> --- get_vm_area_caller()
> __get_vm_area_node
> kzalloc_node
> kmalloc_node
> kmalloc
It looks like CONFIG_FIX_EARLYCON_MEM defaults to y (on x86 anyways),
so this would cause the path that doesn't call ioremam_nocache to be
taken.
I'm guessing that if you specify earycon, then you also need to ensure
that CONFIG_FIX_EARLYCON is set.
You didn't mention which architecture you were using. ARM has an
early_printk which is sort of like an early console.
--
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
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