In certain cases (e.g. toolchain changes) the size of the created EFI
blob can end up triggering a rounding down which breaks the build.
Example:
debian/util/geniso src/bin-combined/ipxe.iso src/bin-i386-pcbios/ipxe.lkrn \
src/bin-x86_64-efi/ipxe.efi
...
++ stat -c %s src/bin-x86_64-efi/ipxe.efi
+ blocks=896
+ mkfs.msdos -C src/bin-combined/iso.dir.uayAjK/efi.img 896
+ mmd -i src/bin-combined/iso.dir.uayAjK/efi.img ::efi
+ mmd -i src/bin-combined/iso.dir.uayAjK/efi.img ::efi/boot
+ mcopy -o -i src/bin-combined/iso.dir.uayAjK/efi.img \
src/bin-x86_64-efi/ipxe.efi ::efi/boot/bootx64.efi
Disk full
This is due to:
echo $(($(stat -c %s "$EFI") / 1024))
872
echo $(($(stat -c %s "$EFI") / 1024 + 55))
927
echo $(((($(stat -c %s "$EFI") / 1024 + 55)/32*32)))
896 <- Rounds DOWN
This is due to size+55 => 927 being "just below" the next 32 iteration
which would be at 928. In many cases that works fine (I don't know how
the +55 was invented, I guess that is for headers). But in some cases
it caps too much eventually ending up in a too small image file.
Rounding up (in bash) usually is "N+1/divisor". Therefore if add +1 before
the rounding for 32 we'd avoid the issue.
I compared the resulting ISO size with former builds and it was still
well within the range of past builds (869,947,948 - now 884).
In some cases there can be rounding issues on the efi content to image
size. In those cases the build will fail with the image not being big
enough.
$ debian/util/geniso src/bin-combined/ipxe.iso src/bin-i386-pcbios/ipxe.lkrn \
src/bin-x86_64-efi/ipxe.efi
Disk full
Avoid this size-off-by-one by adding 1 block to the requested size.
Signed-off-by: Christian Ehrhardt <email address hidden>
