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rpi-make-boot-image: Fix FAT12 image generation #316

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Merged
timg236 merged 1 commit into from
Jul 2, 2025
Merged

rpi-make-boot-image: Fix FAT12 image generation #316

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18 changes: 12 additions & 6 deletions tools/rpi-make-boot-image
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Original file line number Diff line number Diff line change
Expand Up @@ -205,16 +205,22 @@ createstaging() {

IMAGE_SIZE="$((clusters * cluster_size))"

root_dir_sectors="$((((ROOT_DIR_ENTRIES * 32) + cluster_size - 1)/cluster_size))"
# FAT32/FAT16 determined by number of clusters
if [ "$clusters" -gt "65526" ]; then
FAT_SIZE="32"
fat_table_sectors="$(((((clusters + 2)*4) + SECTOR_SIZE - 1)/SECTOR_SIZE))"
else
fat_table_sectors="$(((((clusters + 2)*4) + SECTOR_SIZE - 1)/SECTOR_SIZE))"
elif [ "$clusters" -gt "4085" ]; then
FAT_SIZE="16"
fat_table_sectors="$(((((clusters + 2)*2) + SECTOR_SIZE - 1)/SECTOR_SIZE))"
# Add some sectors based on ROOT_DIR_ENTRIES
root_dir_sectors="$((((ROOT_DIR_ENTRIES * 32) + cluster_size - 1)/cluster_size))"
fat_table_sectors="$((fat_table_sectors + root_dir_sectors))"
fat_table_sectors="$(((((clusters + 2)*2) + SECTOR_SIZE - 1)/SECTOR_SIZE))"
# Add some sectors based on ROOT_DIR_ENTRIES
fat_table_sectors="$((fat_table_sectors + root_dir_sectors))"
else
FAT_SIZE="12"
#12 bits per cluster = 3 bytes for 2 clusters
fat_table_sectors=$(((((clusters + 2)*3+1) / 2 + SECTOR_SIZE - 1)/SECTOR_SIZE))
# Add some sectors based on ROOT_DIR_ENTRIES
fat_table_sectors="$((fat_table_sectors + root_dir_sectors))"
fi
IMAGE_SIZE="$((IMAGE_SIZE + fat_table_sectors * SECTOR_SIZE))"
IMAGE_SIZE="$(((IMAGE_SIZE + 1023)/1024))"
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