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
Regards,
Sukanto
On Jan 29, 2012 12:28 PM, "Dave Hylands" <dhylands@xxxxxxxxx> wrote:
>
> Hi Sukanto
>
> On Sat, Jan 28, 2012 at 10:02 PM, Sukanto Ghosh
> <sukanto.cse.iitb@xxxxxxxxx> wrote:
> > I am kind of lost trying to figure out how can kmallocs work if they
> > are called before kmem_cache_init
> >
> > (e.g. such a case occurs when in start_kernel() we call
> > parse_early_param() (which in turn might call
> > early_serial8250_setup() if earlycon= is used in kernel command-line)
> > before mm_init() (which later calls
> > kmem_cache_init() )
>
> I don't think that you're allowed to call kmalloc during early_setup.
> I don't see where early_serial8250_setup calls kmalloc.
>
> --
> Dave Hylands
> Shuswap, BC, Canada
> http://www.davehylands.com
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