kmalloc before kmem_cache_init

[Dave Hylands]

Hi Sukanto,

On Sat, Jan 28, 2012 at 11:25 PM, Sukanto Ghosh
<sukanto.cse.iitb at gmail.com> 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