1 If you are experiencing hangups/data-aborts when trying to display a BMP image, 2 the following might be relevant to your situation... 3 4 Some architectures cannot handle unaligned memory accesses, and an attempt to 5 perform one will lead to a data abort. On such architectures it is necessary to 6 make sure all data is properly aligned, and in many situations simply choosing 7 a 32 bit aligned address is enough to ensure proper alignment. This is not 8 always the case when dealing with data that has an internal layout such as a 9 BMP image: 10 11 BMP images have a header that starts with 2 byte-size fields followed by mostly 12 32 bit fields. The packed struct that represents this header can be seen below: 13 14 typedef struct bmp_header { 15 /* Header */ 16 char signature[2]; 17 __u32 file_size; 18 __u32 reserved; 19 __u32 data_offset; 20 ... etc 21 } __attribute__ ((packed)) bmp_header_t; 22 23 When placed in an aligned address such as 0x80a00000, char signature offsets 24 the __u32 fields into unaligned addresses (in our example 0x80a00002, 25 0x80a00006, and so on...). When these fields are accessed by U-Boot, a 32 bit 26 access is generated at a non-32-bit-aligned address, causing a data abort. 27 The proper alignment for BMP images is therefore: 32-bit-aligned-address + 2. 28
