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bootimg: Account for FAT filesystem overhead in image size 

Fixes [YOCTO #1852]

The bootimg class wasn't accounting for non-trivial amount of space
required by the directory entries and FATs for the FAT filesystem.

This patch attempts to make an accurate prediction of FAT overhead and
adjusts the image size accordingly. It assumes no more than 16 directory
entries per directory (which fit in a single sector). It also assumes
8.3 filenames. With the ceiling functions rounding up to full sectors
and tracks, these assumptions seem reasonable.

In order to ensure the calculations are accurate, this patch forces the
FAT size to 32, rather than allowing mkdosfs to automatically select 12,
16, or 32 depending on the image being built.

Tested by setting BOOTIMG_EXTRA_SPACE=0 and building core-image-minimal
and core-image-sato for fri2-noemgd from meta-intel.

(From OE-Core rev: 68aa18609c10a3ae2f738930c933fa2a95ce8959)

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
CC: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

Backported to edison by Darren Hart.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Darren Hart 2012-04-11 10:51:11 -07:00 committed by Richard Purdie
parent 4274ebdd00
commit d1c5de9ccb
1 changed files with 36 additions and 9 deletions
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45
meta/classes/bootimg.bbclass
View File

@ -62,19 +62,46 @@ build_boot_bin() {
install -m 444 ${STAGING_LIBDIR}/syslinux/ldlinux.sys ${HDDDIR}/ldlinux.sys
# Determine the 1024 byte block count for the final image.
BLOCKS=`du --apparent-size -ks ${HDDDIR} | cut -f 1`
SIZE=`expr $BLOCKS + ${BOOTIMG_EXTRA_SPACE}`
# Calculate the size required for the final image including the
# data and filesystem overhead.
# Sectors: 512 bytes
# Blocks: 1024 bytes
# Determine the sector count just for the data
SECTORS=$(expr $(du --apparent-size -ks ${HDDDIR} | cut -f 1) \* 2)
# Account for the filesystem overhead. This includes directory
# entries in the clusters as well as the FAT itself.
# Assumptions:
# < 16 entries per directory
# 8.3 filenames only
# 32 bytes per dir entry
DIR_BYTES=$(expr $(find ${HDDDIR} | tail -n +2 | wc -l) \* 32)
# 32 bytes for every end-of-directory dir entry
DIR_BYTES=$(expr $DIR_BYTES + $(expr $(find ${HDDDIR} -type d | tail -n +2 | wc -l) \* 32))
# 4 bytes per FAT entry per sector of data
FAT_BYTES=$(expr $SECTORS \* 4)
# 4 bytes per FAT entry per end-of-cluster list
FAT_BYTES=$(expr $FAT_BYTES + $(expr $(find ${HDDDIR} -type d | tail -n +2 | wc -l) \* 4))
# Use a ceiling function to determine FS overhead in sectors
DIR_SECTORS=$(expr $(expr $DIR_BYTES + 511) / 512)
# There are two FATs on the image
FAT_SECTORS=$(expr $(expr $(expr $FAT_BYTES + 511) / 512) \* 2)
SECTORS=$(expr $SECTORS + $(expr $DIR_SECTORS + $FAT_SECTORS))
# Determine the final size in blocks accounting for some padding
BLOCKS=$(expr $(expr $SECTORS \* 2) + ${BOOTIMG_EXTRA_SPACE})
# Ensure total sectors is an integral number of sectors per
# track or mcopy will complain. Sectors are 512 bytes, and and
# we generate images with 32 sectors per track. This calculation
# is done in blocks, which are twice the size of sectors, thus
# the 16 instead of 32.
SIZE=$(expr $SIZE + $(expr 16 - $(expr $SIZE % 16)))
# track or mcopy will complain. Sectors are 512 bytes, and we
# generate images with 32 sectors per track. This calculation is
# done in blocks, thus the mod by 16 instead of 32.
BLOCKS=$(expr $BLOCKS + $(expr 16 - $(expr $BLOCKS % 16)))
IMG=${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.hddimg
mkdosfs -n ${BOOTIMG_VOLUME_ID} -S 512 -C ${IMG} ${SIZE}
mkdosfs -F 32 -n ${BOOTIMG_VOLUME_ID} -S 512 -C ${IMG} ${BLOCKS}
# Copy HDDDIR recursively into the image file directly
mcopy -i ${IMG} -s ${HDDDIR}/* ::/