[U-Boot] [U-Boot, 1/2, v4] powerpc/mpc85xx: SECURE BOOT- NAND secure boot target for P3041

[aneesh.bansal at freescale.com <aneesh.bansal@freescale.com>]

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Thursday, March 05, 2015 10:38 PM
> To: Bansal Aneesh-B39320
> Cc: u-boot at lists.denx.de; Sun York-R58495; Gupta Ruchika-R66431
> Subject: Re: [U-Boot, 1/2, v4] powerpc/mpc85xx: SECURE BOOT- NAND
> secure boot target for P3041
> 
> On Thu, 2015-03-05 at 01:26 -0600, Bansal Aneesh-B39320 wrote:
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Thursday, March 05, 2015 2:41 AM
> > > To: Bansal Aneesh-B39320
> > > Cc: u-boot at lists.denx.de; Sun York-R58495; Gupta Ruchika-R66431
> > > Subject: Re: [U-Boot, 1/2, v4] powerpc/mpc85xx: SECURE BOOT- NAND
> > > secure boot target for P3041
> > >
> > > Where does the 3.5G limitation come from?  Even if the physical
> > > address needs to be elsewhere due to bootrom constraints, we should
> > > be able to map it wherever we want in the TLB once U-Boot takes
> control.
> > >
> > The 3.5G limitation comes from BootROM in case of secure Boot.
> > Initially U-Boot has to run from CPC configured as SRAM with address
> > Within 3.5G. Once U-boot has relocated to DDR, we have removed the
> > Corresponding TLB entry.
> 
> Again, you could relocate the virtual address of L3 much earlier.
> 
> -Scott
> 
Are you suggesting the following:
1.  PBI Commands to configure CPC as SRAM with address 0xBFF0_0000.
2.  Compile U-boot with TEXT BASE as 0xFFF40000.
3.  Copy the U-boot from NAND via PBI commands to CPC (SRAM) on address 0xBFF4_0000
4.  The BootROM will validate the U-boot and transfer the control to 0xBFFF_FFFC.
5.  When U-boot is executing, then in the last 4K code, when shifting from AS=0 to AS=1, 
      we change the address of SRAM from 0xBFF0_0000 to 0xFFF0_0000. (Similar to what is done for NOR Boot)

- Aneesh