[PATCH 1/1] arm: mmu: catch NULL pointer dereferences

[Sascha Hauer]

On Mon, Sep 02, 2013 at 12:24:06PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 11:05 Mon 02 Sep     , Sascha Hauer wrote:
> > On Sat, Aug 31, 2013 at 05:54:22PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > > For high vectors if memory start at 0x0. We have to
> > > live without being able to catch NULL pointer dereferences.
> > > 
> > Why not add the check to vectors_init() instead of passing this as
> > argument?
> > 
> > I must say I'm not entirely happy with this approach. Being able to
> > catch NULL pointer derefs is really a good thing. When exactly does the
> > faulting zero SDRAM page become a problem for you? obviously something
> > like
> > 
> > cp /somehing /dev/ram0
> > 
> > does not work. Some care must probably be taken when setting up the
> > kernel parameters. Are these the problems or is there something else?
> yes it's get issue with uImage that get data load there :(
> 
> as I can not control the load addr from uImage :(
> 
> and on ux5x0 and arm board I have ddr starting at 0x0

Maybe we should add some hook which dynamically enables/disables the
zero page. The bootm code could then disable it.

Anyway, for now we can also apply the current patch, but please move the
is_start_zero test to vectors_init().

Sascha

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