[U-Boot] [PATCH 3/3] powerpc/mpc85xx: SECURE BOOT- Disable law 0 for non PBL platforms

[Scott Wood]

On Mon, 2014-01-27 at 01:28 -0600, Bansal Aneesh-B39320 wrote:
> > > ISBC creates a LAW 0 entry for non PBL platforms, which is not
> > > disabled before transferring the control to uboot.
> > > The LAW 0 entry has to be disabled.
> > >
> > > Signed-off-by: Aneesh Bansal <aneesh.bansal at freescale.com>
> > > ---
> > >  arch/powerpc/cpu/mpc85xx/start.S | 58 ++++++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 58 insertions(+)
> > >
> > > diff --git a/arch/powerpc/cpu/mpc85xx/start.S b/arch/powerpc/cpu/mpc85xx/start.S
> > > index 5440bf5..2b2c4dd 100644
> > > --- a/arch/powerpc/cpu/mpc85xx/start.S
> > > +++ b/arch/powerpc/cpu/mpc85xx/start.S
> > > @@ -116,6 +116,64 @@ _start_e500:
> > >       mtspr   SPRN_HDBCR0, r3
> > >  #endif
> > >
> > > +#if defined(CONFIG_SECURE_BOOT) && defined(CONFIG_E500) && \
> > > +                                             !defined(CONFIG_E500MC)
> > 
> > CONFIG_E500 can be assumed in this file.
> > 
> > > +     /* ISBC creates a LAW 0 entry for non PBL platforms,
> > > +      * which is not disabled before transferring the control to uboot.
> > > +      * Disable the LAW 0 entry here.
> > > +      */
> > 
> > Could you explain what this LAW 0 entry is for, why we don't need it,
> > and why we can't wait until later to clear it?
> > 
> > -Scott
> 
> Boot ROM creates a LAW 0 entry for IFC and at entry at U-boot during
> secure boot, we want to have the same environment as in case of
> Non-secure Boot. So, this LAW entry is being removed at start.

But in the secure boot case aren't you currently running from that LAW?

And I don't think wanting to have the same environment is a good reason
for injecting more code into the already messy start.S, if there isn't a
good reason why it can't be done later.

-Scott