A simple bootloader…

David — Thu, 11 Jun 2009 06:21:19 +0000

If you have ever used a Linux distro on an embedded system you know that a bootloader is a necessity. I’ve been working with PetaLinux for the Xilinx MicroBlaze and we have been using FS-boot to launch U-boot and then bring up Peta. However, recently I switched to BlueCat linux to take advantage of the MicroBlaze’s MMU. However, BlueCat doesn’t document a clear way to boot from flash. Below is some simple code to boot BlueCat. Note: the concept was taken from a Xilinx app note.

#include 
#define KDI_FLASH_LOC 0xXXXXXXXX //location of the linux image in flash
#define KDI_DDR_LOC 0xXXXXXXXX //location in DDR that you want your image to end up
#define KDI_LEN 0xXXXXXXXX //length of your image in bytes

main(){

uint8_t* kdi_flash_ptr = (uint8_t*)KDI_FLASH_LOC;
uint8_t* kdi_ddr_ptr = (uint8_t*)KDI_DDR_LOC;

void* laddr;

memcpy(kdi_flash_ptr, kdi_ddr_ptr, KDI_LEN);

laddr = (void*)KDI_DDR_LOC;
(*laddr)();

}

You can use XPS to load your KDI file into flash, and then compile the bootloader into your bitstream, load the FPGA, and you are off!

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A simple bootloader…