Generate ivt binary for use when running an imx6 SoC in HAB mode. Helper towards signing kernel images.

gen_ivt.py

 def gen_ivt(loadaddr, image_file):                                                                                          
    '''Generate imx SoC ivt                                                                                                 
    Args:                                                                                                                    
    loadaddr    int. Hex representing load address in ram for uboot.                                                        
                Can be obtained from your u-boot.cfg build file.
    image_file  string. filename and path to binary image. If 
                generating ivt for signing kernel image, ensure kernel
                image file is pre-padded.
                
    returns:
    Generates binary file called ivt.bin which can be appended to kernel.
    '''
    import os
    
    img_size = os.stat(image_file).st_size
    output_file = 'ivt.bin'    

    # Shouldn't change. Tag=0xD1, Length=0x0020, Ver=0x41
    ivt_header = 0x412000D1
    
    # mem size boundary
    mem_boundary = 0x1000 # 4096 bytes
    
    # Jump Location
    jump_loc = loadaddr + mem_boundary
    
    # ivt size 32 bytes. Fixed.
    ivt_size = 0x20
    
    # Self pointer
    self_pointer = loadaddr + img_size
    
    # csf pointer
    csf_pointer = self_pointer + ivt_size
    print('Creating ivt.\n{} size:{}'.format(image_file,hex(img_size)))
    
    with open(output_file,'wb') as ivt_file:
        ivt_file.write((ivt_header).to_bytes(4,byteorder="little"))
        ivt_file.write((jump_loc).to_bytes(4,byteorder="little"))
        ivt_file.write((0x0).to_bytes(4,byteorder="little")) # Reserved
        ivt_file.write((0x0).to_bytes(4,byteorder="little")) # DCD pointer
        ivt_file.write((0x0).to_bytes(4,byteorder="little")) # Boot data
        ivt_file.write((self_pointer).to_bytes(4,byteorder="little"))
        ivt_file.write((csf_pointer).to_bytes(4,byteorder="little"))
        ivt_file.write((0x0).to_bytes(4,byteorder="little")) # Reserved
        
    print('New {} size is {}'.format(output_file,os.stat(output_file).st_size))