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cdrtools-native: fix booting EFI ISO live failed

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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>
This commit is contained in:
Hongxu Jia 2025-04-26 16:03:51 +08:00 committed by Richard Purdie
parent 55fcffc08c
commit 7ff5ecce28
2 changed files with 70 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
meta/recipes-devtools/cdrtools/cdrtools-native_3.01.bb
View File

@ -15,6 +15,7 @@ SRC_URI = " \
file://0001-Don-t-set-uid-gid-during-install.patch \
file://riscv64-linux-gcc.rul \
file://gcc14-fix.patch \
file://0001-fix-nsectors-exceeds-0xffff-situation.patch \
"
SRC_URI[md5sum] = "7d45c5b7e1f78d85d1583b361aee6e8b"

69
meta/recipes-devtools/cdrtools/cdrtools/0001-fix-nsectors-exceeds-0xffff-situation.patch Normal file
View File

@ -0,0 +1,69 @@
From ab6b5ee4c23099bf15ddd145fdf1ff4f5e34e802 Mon Sep 17 00:00:00 2001
From: Hongxu Jia <hongxu.jia@windriver.com>
Date: Sat, 26 Apr 2025 03:38:32 +0000
Subject: [PATCH] fix nsectors exceeds 0xffff situation
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)
If the size of efi.img > 32MB, the partition table will be truncated
in ISO, which caused UEFI system or grub-efi read efi.img broken
occasionally.
In this patch, nsectors means sector count, if it exceeds 0xffff,
truncate to 0xffff and set selection criteria type = 2, then save
extra nsectors to vendor unique selection criteria
[1]https://pdos.csail.mit.edu/6.828/2017/readings/boot-cdrom.pdf
Upstream-Status: Inappropriate [upstream https://sourceforge.net/projects/cdrtools/ is not alive since 2019]
Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
---
mkisofs/eltorito.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/mkisofs/eltorito.c b/mkisofs/eltorito.c
index 5dd04bc..a391003 100644
--- a/mkisofs/eltorito.c
+++ b/mkisofs/eltorito.c
@@ -568,6 +568,34 @@ fill_boot_desc(boot_desc_entry, boot_entry)
fprintf(stderr, "Extent of boot images is %d\n",
get_733(de->isorec.extent));
#endif
+
+ // Boot sectors exceeds 0xffff
+ if (nsectors > 0xffff) {
+ unsigned int extra_nsectors = nsectors - 0xffff;
+
+ fprintf(stderr, "Warning: Boot sectors 0x%x(%u) exceeds 0xffff(65535), save extra %u to pad2\n",
+ nsectors, nsectors, extra_nsectors);
+
+ // Set nsectors to maximum 0xffff(65535)
+ nsectors = 0xffff;
+
+ // Offset : 0C byte
+ // Type : Byte
+ // Description: Selection criteria type. This defines a vendor unique format
+ // for bytes 0D-1F.
+ // The following formats is reserved by Yocto:
+ // 2 - Save extra sector count to vendor unique selection criteria
+ boot_desc_entry->pad2[0] = 2;
+
+
+ // Offset : 0D-0E-0F-10 byte
+ // Type : D Word
+ // Description: Save extra sector count to vendor unique selection criteria.
+ // It takes 4 bytes in pad2, starting at pad2[1]
+ set_731(&boot_desc_entry->pad2[1], extra_nsectors);
+
+ }
+
set_721(boot_desc_entry->nsect, (unsigned int) nsectors);
set_731(boot_desc_entry->bootoff,
(unsigned int) get_733(de->isorec.extent));
--
2.44.1