On 5/18/22 5:55 AM, Claus Stovgaard wrote:
Hi folks.
I think the BOOTDD_EXTRA_SPACE is used incorrectly in bootimg-efi.py
and bootimg-pcbios.py?
The background is that I am forced to create a rather small efi
partition of 25 MB. Not a big problem I thought, as the kernel, plus
initrd is only 12 MB. But the resulting partition was 28 MB.
After some digging I found this identical part in bootimg-efi and
bootimg-pcbios.
blocks = int(out.split()[0])
extra_blocks = part.get_extra_block_count(blocks)
if extra_blocks < BOOTDD_EXTRA_SPACE:
extra_blocks = BOOTDD_EXTRA_SPACE
blocks += extra_blocks
logger.debug("Added %d extra blocks to %s to get to %d total
blocks",
extra_blocks, part.mountpoint, blocks)
So we calculate some extra blocks and if the extra blocks is less than
the requested extra space we add BOOTDD_EXTRA_SPACE.
Why the value of 16 MB.
My guess was that it is for forcing mkdosfs to do a fat16 and not a
fat12, it need minimum 16 MB
A quick test showed that 8 MB gives fat12 and 16 MB gives fat16.
clst@clst-linux:~$ mkdosfs -n test -C test.img $(( 4096 * 2 )) -v
mkfs.fat 4.1 (2017-01-24)
mkfs.fat: warning - lowercase labels might not work properly with DOS
or Windows
test.img has 64 heads and 32 sectors per track,
hidden sectors 0x0000;
logical sector size is 512,
using 0xf8 media descriptor, with 16384 sectors;
drive number 0x80;
filesystem has 2 12-bit FATs and 8 sectors per cluster.
FAT size is 8 sectors, and provides 2041 clusters.
There are 8 reserved sectors.
Root directory contains 512 slots and uses 32 sectors.
Volume ID is bbbd3650, volume label test .
clst@clst-linux:~$ rm test.img
clst@clst-linux:~$ mkdosfs -n test -C test.img $(( 4096 * 4 )) -v
mkfs.fat 4.1 (2017-01-24)
mkfs.fat: warning - lowercase labels might not work properly with DOS
or Windows
test.img has 64 heads and 32 sectors per track,
hidden sectors 0x0000;
logical sector size is 512,
using 0xf8 media descriptor, with 32768 sectors;
drive number 0x80;
filesystem has 2 16-bit FATs and 4 sectors per cluster.
FAT size is 32 sectors, and provides 8167 clusters.
There are 4 reserved sectors.
Root directory contains 512 slots and uses 32 sectors.
Volume ID is bc573a89, volume label test
So would a better solution not be to rename it to BOOTDD_MINIMUM_SIZE
or something like this, and change the code to something like below:
blocks = int(out.split()[0])
blocks += part.get_extra_block_count(blocks)
if blocks < BOOTDD_MINIMUM_SIZE:
blocks = BOOTDD_MINIMUM_SIZE
logger.debug("Set %s to %d total blocks", part.mountpoint, blocks)
Can see the current behavior is pretty old - from 2014
https://git.yoctoproject.org/poky/commit/?id=df634f3b1e02aa18f84b4b74f13c7260a21691aa
Please comment about the BOOTDD_EXTRA_SPACE
What do you think about my proposal.
I think in your case you can set BOOTDD_EXTRA_SPACE to 0 perhaps to get
desired behavior. Your analysis is correct. BOOTDD_EXTRA_SPACE ensures
that much of space it available, but perhaps what we need is minimum size.
Regards
Claus
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