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In ISO live, if the size of efi.img > 32MB, and copy EFI application
(bootx64.efi) to efi.img behind of kernel and initrd, UEFI system
could not find EFI application bootx64.efi
Using QEMU+OVMF to boot ISO live image, press ESC to enter UEFI shell:
...
Shell> ls FS0:\
Directory of: FS0:\
04/05/2011 23:00 12,985,344 bzImage
04/05/2011 23:00 <DIR> 2,048 EFI
04/05/2011 23:00 20,494,696 initrd
04/05/2011 23:00 26 startup.nsh
3 File(s) 33,480,066 bytes
1 Dir(s)
Shell> ls FS0:\EFI
Directory of: FS0:\EFI
0 File(s) 0 bytes
0 Dir(s)
...
In following case, add 64MB extra space to bootable image efi.img,
and the partition table of EFI is truncated to 26.3M
$ echo 'IMAGE_FSTYPES:pn-core-image-minimal = " live"' >> conf/local.conf
$ echo 'MACHINE_FEATURES:append = " efi pcbios"' >> conf/local.conf
$ echo '# 64MB extra space to bootable image efi.img' >> conf/local.conf
$ echo 'BOOTIMG_EXTRA_SPACE = "65535"' >> conf/local.conf
$ bitbake core-image-minimal
$ fdisk -l tmp/deploy/images/qemux86-64/core-image-minimal-qemux86-64.rootfs.iso
...
Device Boot Start End Sectors Size Id Type
tmp/deploy/images/qemux86-64/core-image-minimal-qemux86-64.rootfs.iso1 * 0 376831 376832 184M 0 Empty
tmp/deploy/images/qemux86-64/core-image-minimal-qemux86-64.rootfs.iso2 120 54079 53960 26.3M ef EFI (FAT-12/16/32)
According to page 11: `Figure 5 - Section Entry' in El Torito Bootable
CD-ROM Format Specification [1]. The sector count takes 2 byte which
means max sector count is 0xffff (65535), for 512-byte sector, the
size of bootable image is no more than 32MB (65536 * 512 / 1024 / 1024)
This commit truncate to 32MB if image size larger than 32MB, and
report a warning, then save the extra image sector count to
vendor unique selection criteria
After apply this commit, the partition table of EFI is truncated to 32M
$ fdisk -l tmp/deploy/images/qemux86-64/core-image-minimal-qemux86-64.rootfs.iso
...
Device Boot Start End Sectors Size Id Type
tmp/deploy/images/qemux86-64/core-image-minimal-qemux86-64.rootfs.iso1 * 0 376831 376832 184M 0 Empty
tmp/deploy/images/qemux86-64/core-image-minimal-qemux86-64.rootfs.iso2 120 65654 65535 32M ef EFI (FAT-12/16/32)
[1]https://pdos.csail.mit.edu/6.828/2017/readings/boot-cdrom.pdf
(From OE-Core rev: 259bb8907d8bfe1217e88a3b6935c160e5a92f8d)
Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>