How to upgrade from PAE 36bit Linux to 64bit Linux

[bensung]

I have a custom board using P5040 (e5500 core). I am considering to upgrade the kernel from 36bit PAE mode to 64 bit, but I wonder what are the works involved.

Am I correct to assume the following?

• For uboot, no change is required. It can stay in 32 bit mode.
• For the Linux kernel, upgrading to 64 bit mode is just a matter of setting "CONFIG_PPC64" in defconfig ?
• For the drivers, since they are written for kernel in PAE mode (36bit), they would probably just work in 64bit kernel. Drivers for kernel in PAE mode have already been updated to use 64bit variables to hold the 36bit physical address.
• For user space applications, this kernel change should be transparent.

Thanks,

Ben

[bpe]

Yes, your statements are correct, a few remarks  follow:

1. Two kernel configuration options are required for 64-bit kernel for
   NXP embedded PowerPC based processors, CONFIG_PPC64 and
   CONFIG_PPC_BOOK3E_64
   
2. NXP QorIQ SDK provides a verified 64-bit kernel for your processor.
   QorIQ SDK can be obtained from here:
    http://www.nxp.com/products/software-and-tools/run-time-software/linux-sdk/linux-sdk-for-qoriq-proce...
   
   SDK online documentation is at this link:
   
   https://freescale.sdlproducts.com/LiveContent/web/pub.xql?c=t&action=home&pub=QorIQ_SDK&lang=en-US
   
3. u-Boot is 32-bit, but it must be aware of extended pointers. Below
   is an excerpt from include/configs/P5040DS.h:

    #define CONFIG_P5040DS
    #define CONFIG_PHYS_64BIT
    #define CONFIG_PPC_P5040

   A good discussion can be found in appnote AN4064.
   
  

[bensung]

Below is the link to AN4064. This is actually the document which I followed to migrate from 32bit to...

http://www.nxp.com/files/32bit/doc/app_note/AN4064.pdf