[PATCH v3 0/9] Improve ld.lld-21+ compatibility when building i386-pc target

* [PATCH v3 0/9] Improve ld.lld-21+ compatibility when building i386-pc target
@ 2026-02-14  1:05 Nicholas Vinson
  2026-02-14  1:05 ` [PATCH v3 1/9] i386/pc/int.h: conditionally apply regparm attr Nicholas Vinson
                   ` (9 more replies)
  0 siblings, 10 replies; 18+ messages in thread
From: Nicholas Vinson @ 2026-02-14  1:05 UTC (permalink / raw)
  To: grub-devel, dkiper, floppym; +Cc: Nicholas Vinson

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: conditionally apply regparm attr.
  grub-core: Update kernel image generation
  i386-cygwin-img-ld.sc -> i386-cygwin-img.lds
  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
  conf/i386-cygwin-img.lds: Update to use _grub_text_base symbol

 .gitignore                                    |  3 +-
 INSTALL                                       |  1 -
 acinclude.m4                                  | 18 ++++--
 conf/Makefile.extra-dist                      |  3 +-
 ...6-cygwin-img-ld.sc => i386-cygwin-img.lds} |  1 +
 conf/i386-pc-kernel.lds                       | 51 ++++++++++++++++
 configure.ac                                  | 61 ++++++++++++-------
 grub-core/Makefile.core.def                   | 31 +++++-----
 include/grub/i386/pc/int.h                    |  5 +-
 m4/ax_check_link_flag.m4                      | 53 ++++++++++++++++
 10 files changed, 181 insertions(+), 46 deletions(-)
 rename conf/{i386-cygwin-img-ld.sc => i386-cygwin-img.lds} (97%)
 create mode 100644 conf/i386-pc-kernel.lds
 create mode 100644 m4/ax_check_link_flag.m4

-- 
2.53.0


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