On Tue, Mar 03, 2026 at 09:41:12PM -0500, Nicholas Vinson wrote:
> Starting with ld.llvm-21, any attempt create a non-relocatable binary and set
> one more secton addresses below 0x400000 results in a linker error.
> Furthermore,
> the differences between ld.bfd and ld.lld made finding a proper set of
> command-line flags tht worked with both linkers and bypass the image base
> address restriction difficult. Therefore, the approach of using a custom
> linker
> script was adopted to solve the issue.
>
> This approach was tested using:
>
> ../configure CC=clang CXX=clang++ LDFLAGS="-fuse-ld=lld"
> TARGET_LDFLAGS="-fuse-ld=lld" --with-platform=pc
> ../configure CC=clang CXX=clang++ --with-platform=pc (both with ld.lld as the
> default and ld.bfd as the default)
> ../configure CC=gcc CXX=g++ --with-platform=pc
>
> and a VM was used for testing. To build the disk images the VM was booted
> with,
> the following scripts were used:
>
> EFI disk:
> --- /dev/null 2026-01-18 13:24:44.262332704 -0500
> +++ efi_disk_image.sh 2026-01-25 11:17:33.554420324 -0500
> @@ -0,0 +1,23 @@
> +#!/bin/sh
> +
> +set -xe
> +
> +dd if=/dev/zero of=grub.img bs=1M count=100 status=progress
> +
> +sfdisk --force --no-reread --no-tell-kernel grub.img <<EOF
> +label: gpt
> +label-id: ABEB6772-65C7-4391-BF21-B616916286B9
> +size=1M, type=21686148-6449-6E6F-744E-656564454649,
> uuid=9892A604-439E-4401-A372-AAD5E99EADBB
> +type=0FC63DAF-8483-4772-8E79-3D69D8477DE4,
> uuid=FCE5EBB3-C887-4FDE-93C5-7670CC3914BF
> +EOF
> +
> +LOOP_DEV=$(losetup --show -fP grub.img)
> +sleep 1
> +
> +mkfs.ext4 -F "${LOOP_DEV}p2"
> +
> +mount "${LOOP_DEV}p2" /mnt/gentoo
> +./grub-install -v --directory ./grub-core --locale-directory
> /usr/share/locale --boot-directory=/mnt/gentoo "${LOOP_DEV}"
> +
> +umount "${LOOP_DEV}p2"
> +losetup -d "${LOOP_DEV}"
> --
>
> MBR image:
> --- /dev/null 2026-01-18 13:24:44.262332704 -0500
> +++ mbr_disk_image.sh 2026-01-25 11:17:24.129208591 -0500
> @@ -0,0 +1,22 @@
> +#!/bin/sh
> +
> +set -xe
> +
> +dd if=/dev/zero of=grub.img bs=1M count=100 status=progress
> +
> +sfdisk --force --no-reread --no-tell-kernel grub.img <<EOF
> +label: dos
> +label-id: 0x12345678
> +type=83, bootable
> +EOF
> +
> +LOOP_DEV=$(losetup --show -fP grub.img)
> +sleep 1
> +
> +mkfs.ext4 -F -O ^has_journal "${LOOP_DEV}p1"
> +
> +mount "${LOOP_DEV}p1" /mnt/gentoo
> +./grub-install -v --directory ./grub-core --locale-directory
> /usr/share/locale --boot-directory=/mnt/gentoo "${LOOP_DEV}"
> +
> +umount "${LOOP_DEV}p1"
> +losetup -d "${LOOP_DEV}"
> --
>
> In all cases, the VM successfully booted to the standard GRUB prompt.
>
> Nicholas Vinson (9):
> i386/pc/int.h: move GRUB_MACHINE_PCBIOS ifdef
> grub-core: Update kernel image generation
> Revert "configure: Print a more helpful error if autoconf-archive is
> not installed"
> Revert "configure: Check linker for --image-base support"
> Revert "INSTALL: Add note that the GNU Autoconf Archive may be needed"
> configure: drop -Ttext checks for i386-pc
> configure.ac: Add --image-base check for non-i386
> i386-cygwin-img-ld.sc -> i386-cygwin-img.lds
> conf/i386-cygwin-img.lds: Update to use _grub_text_base symbol
In general Reviewed-by: Daniel Kiper <[email protected]> but...
diff --git a/configure.ac b/configure.ac
index 560c8a320..d19fb625d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1462,8 +1462,8 @@ elif test x$grub_cv_target_cc_link_format = x-mi386pe ||
test x$grub_cv_target_c
TARGET_IMG_LDSCRIPT='$(top_srcdir)'"/conf/i386-cygwin-img.lds"
TARGET_IMG_LDFLAGS="-Wl,-T${TARGET_IMG_LDSCRIPT}"
TARGET_IMG_LDFLAGS_AC="-Wl,-T${srcdir}/conf/i386-cygwin-img.lds"
- TARGET_IMG_BASE_LDOPT="-Wl,--defsym,_grub_text_base"
- TARGET_IMG_BASE_LDOPT_ARG_SEP=","
+ TARGET_IMG_BASE_LDOPT="-Wl,--defsym=_grub_text_base"
+ TARGET_IMG_BASE_LDOPT_ARG_SEP="="
TARGET_IMG_CFLAGS=
else
TARGET_APPLE_LINKER=0
@@ -1486,7 +1486,7 @@ else
])])
TARGET_IMG_BASE_LDOPT_ARG_SEP=","
else
- TARGET_IMG_BASE_LDOPT="-Wl,--defsym,_grub_text_base"
+ TARGET_IMG_BASE_LDOPT="-Wl,--defsym=_grub_text_base"
TARGET_IMG_BASE_LDOPT_ARG_SEP="="
TARGET_IMG_LDSCRIPT='$(top_srcdir)'"/conf/i386-pc-kernel.lds"
TARGET_IMG_LDFLAGS="${TARGET_IMG_LDFLAGS} -Wl,-T${TARGET_IMG_LDSCRIPT}"
The ld man is clear: --defsym=symbol=expression
If you are OK with proposed changes I will make them for you.
Daniel
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