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How to run t1040d4rdb with 32 bit physical address space

Question asked by James Lee on Sep 6, 2017
Latest reply on Sep 8, 2017 by James Lee

I have t1040d4rdb boards and learned that Linux Kernel and Device Tree shipped with the board is compiled for 36 bit physical address support.  I found an application note "Utilizing 36-Bit Physical Addressing in U-Boot and Linux" and tried to recompile Linux Kernel and Device Tree for 32 bit addressing.

 

I am running into several issues:

- When I run menuconfig to deselect CONFIG_PHYS_64BIT option, it did not allow me to deselect CONFIG_PHYS_64BIT.  I could not deselect CONFIG_SWIOTLB option either.  I then manually changed .config file to deselect the following kernel options:

  • CONFIG_PTE_64BIT 
  • CONFIG_PHYS_64BIT
  • CONFIG_ARCH_PHYS_ADDR_T_64BIT
  • CONFIG_ARCH_DMA_ADDR_T_64BIT
  • CONFIG_SWIOTLB
  • CONFIG_PHYS_ADDR_T_64BIT
  • CONFIG_PCI_BUS_ADDR_T_64BIT

 

- When I looked for device tree, I could not find any device tree files with 32 bit address for t1040rdb.  All device trees for t1040rdb are currently written for 36 bit address.

 

Could you provide a step by step instructions for how to build Linux kernel and Device tree with 32 bit address?

I believe that u-boot currently loaded on t1040d4rdb has 32 bit u-boot but I could not confirm.

 

Thanks in advance.

James

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