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GR716-DS-UM, May 2019, Version 1.29
504
www.cobham.com/gaisler
GR716
51.2.6 Application software image format
Application software image files are located in ASM from where they are loaded by the Boot software
Application loader. An image consists of an image header, a number of image section headers, and a
variable number of data blocks. All addresses (entry point and data destination addresses) must be
aligned to 32-bit words.
When the application software is loaded the image header read is always stored in top of memory. The
application software can determine its origin by reading the stored header in the local data memory.
The image header start is always set to
’boot_image_header’
from the end of the last address in the
local data memory.
Table 677.
Image header
Field
Type
Description
id
32-bit word
User defined section. The values does not affect Boot
software execution.
ep
1)
32-bit word
Application software entry point
stp
32-bit word
Application stack pointer
sections 0
1)
image section header
Section layout defined in table below.
sections [1 ..7]
image section header
Section layout defined in table below.
cksum
16 -bit word
16-bit ISO checksum as defined in [ECSS-E7041],
annex A. Calculated over all fields of the image header.
Reserved
16-bit word
Reserved, set to zero
Note 1:
See errata for details about entry point located in section0
Table 678.
Image section header
Field
Type
Description
flags
32-bit word
Bit 0: ENABLE - This section shall be copied to RAM.
Bit 31..1: RESERVED - Must be 0
source
32-bit word
Location of source data block, expressed as number of
32-bit words relative to image header. (Note: Offset is
not relative to section header.)
dest
32-bit word
Absolute destination address
length
32-bit word
Length of section data block in 32-bit words.
datacksum
16-bit word
Data block checksum over data[0]..data[length-1].
16-bit ISO checksum as defined in [ECSS-E7041],
annex A.
Reserved
16-bit word
Reserved
Table 679.
Image section data block
Field
Type
Description
data[0]
32-bit word
Data word 0
data[1]
32-bit word
Data word 1
...
...
...
data[length-1]
32-bit word
Data word length-1