Improve ld.lld-21+ compatibility when building i386-pc target

Modern compilers are becoming more strict and are starting to warn when certain attributs are ignored. The regparam attribute is such an attribute.

Update the code so the regparam attribute is only appled when building against i386 targets as that is the only scenario when it is not ignored.

Signed-off-by Nicholas Vinson <[email protected]>

---
 include/grub/i386/pc/int.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

include/grub/i386/pc/int.h +4 -1

index a60104001..4b569ca25 100644
@@ -24,7 +24,10 @@
 
 void EXPORT_FUNC (grub_bios_interrupt) (grub_uint8_t intno,
                                        struct grub_bios_int_registers
 *regs)
-     __attribute__ ((regparm(3)));
+#if defined(__i386__) && !defined(__x86_64__)
+     __attribute__ ((regparm(3)))
+#endif
+;
 
 #ifdef GRUB_MACHINE_PCBIOS

extern struct grub_i386_idt *EXPORT_VAR(grub_realidt);
--
2.53.0

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The i386-pc kernel image fails to build because of changes made to address ld.lld-21 and newer linking issues. Specifically, with ld.lld-21, if you try to set the text section address below image base address when linking a non-relocatable binary, ld.lld wil fail to link.

Switching to using a customized linker script solves the issue and is a more robost solution to supporting multiple linkers than attempting to find a set of command-line flags that satisified all supported linkers and links the kernel properly. In the worst case, continued use of command-line flags could result in having to create code branches to support various linkers.

For example, when dealing with just ld.bfd and ld.lld, the behavioral differences between the two made finding a proper subset of flags that worked impossible. The previous attempt dropped -Ttext for --image-base, which has been proven not to work. The simplest correction, -Wl,--image-base=0 -Wl,-Ttext, did not work because that option resulted in a GRUB kernel that entered into a tight infinite refresh loop.

Moreover, ld.lld does not order the sections the same way ld.bfd does, and that results in object files with gaps or holes when sections are stripped. I suspect, but did not investigate, that this plays a role in the infinite refresh loop I mentioned earlier.

The easiest way to resolve all this is to use customized linker scripts. These scripts, by default, override any default configuration the linker would otherwise impose, allow for complete control in aligning sections, and allows GRUB to specify where in the load segment each section goes.

This change does require linkers to support the --defsym flag, which requires its argument to be of the form 'sym=address' as 'sym address' is not supported.

Signed-off-by Nicholas Vinson <[email protected]>

---
 conf/Makefile.extra-dist    |  1 +
 conf/i386-pc-kernel.lds     | 51 +++++++++++++++++++++++++++++++++++++
 grub-core/Makefile.core.def | 31 +++++++++++-----------
 3 files changed, 68 insertions(+), 15 deletions(-)
 create mode 100644 conf/i386-pc-kernel.lds

conf/Makefile.extra-dist +1 -0

index d22b6c862..892df8208 100644
@@ -17,6 +17,7 @@ EXTRA_DIST += docs/grub.cfg
 EXTRA_DIST += docs/osdetect.cfg
 
 EXTRA_DIST += conf/i386-cygwin-img-ld.sc
+EXTRA_DIST += conf/i386-pc-kernel.lds
 
 EXTRA_DIST += grub-core/Makefile.core.def
 EXTRA_DIST += grub-core/Makefile.gcry.def

conf/i386-pc-kernel.lds new file +51 -0

new file mode 100644
index 000000000..d40c7736c
@@ -0,0 +1,51 @@
+ENTRY(_start)
+
+/*
+ * Align sections to a 16-byte boundary. This guarantees ABI compatibility with
+ * C generated code
+ */
+SECTION_ALIGN = 0x10;
+
+PHDRS {
+    text PT_LOAD FLAGS(7) /* PF_R | PF_W | PF_X */;
+}
+
+SECTIONS
+{
+    /*
+     * Set section alignment to 1. This allows sections to be aligned without
+     * creating holes in the VMA space or gaps in the file.
+     */
+    . = _grub_text_base;
+    .text ALIGN(0x1) : {
+        _start = .;
+        *(.text .text.*)
+        . = ALIGN(SECTION_ALIGN);
+    } :text
+    .rodata ALIGN(0x1) : {
+        *(.rodata .rodata.*)
+        . = ALIGN(SECTION_ALIGN);
+    } :text
+    .module_license ALIGN(0x1) : {
+        *(.module_license)
+        . = ALIGN(SECTION_ALIGN);
+    } :text
+    .data ALIGN(0x1) : {
+        *(.data .data.*)
+        . = ALIGN(SECTION_ALIGN);
+        _edata = .;
+    } :text
+    .bss ALIGN(0x1) : {
+        __bss_start = .;
+        *(.bss .bss.*)
+        *(COMMON)
+        . = ALIGN(SECTION_ALIGN);
+        _end = .;
+    } :text
+    /DISCARD/ : {
+        *(.interp)
+        *(.note*)
+        *(.comment)
+        *(.build-id)
+    }
+}

grub-core/Makefile.core.def +0 -0

index 0cf155128..1a91e53d6 100644

grub-core/Makefile.core.def +14 -14

 };
 
 transform_data = {

@@ -82,21 +83,21 @@ kernel = {
   riscv64_efi_stripflags   = '--strip-unneeded -K start -R .note -R .comment -R .note.gnu.gold-version -R .eh_frame';
 
   i386_pc_ldflags          = '$(TARGET_IMG_LDFLAGS)';
-  i386_pc_ldflags          = '$(TARGET_IMG_BASE_LDOPT),0x9000';
+  i386_pc_ldflags          = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x9000';
   i386_qemu_ldflags        = '$(TARGET_IMG_LDFLAGS)';
-  i386_qemu_ldflags        = '$(TARGET_IMG_BASE_LDOPT),0x9000';
+  i386_qemu_ldflags        = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x9000';
   i386_coreboot_ldflags    = '$(TARGET_IMG_LDFLAGS)';
-  i386_coreboot_ldflags    = '$(TARGET_IMG_BASE_LDOPT),0x9000';
+  i386_coreboot_ldflags    = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x9000';
   i386_multiboot_ldflags   = '$(TARGET_IMG_LDFLAGS)';
-  i386_multiboot_ldflags   = '$(TARGET_IMG_BASE_LDOPT),0x9000';
+  i386_multiboot_ldflags   = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x9000';
   i386_ieee1275_ldflags    = '$(TARGET_IMG_LDFLAGS)';
-  i386_ieee1275_ldflags    = '$(TARGET_IMG_BASE_LDOPT),0x10000';
+  i386_ieee1275_ldflags    = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x10000';
   i386_xen_ldflags         = '$(TARGET_IMG_LDFLAGS)';
-  i386_xen_ldflags         = '$(TARGET_IMG_BASE_LDOPT),0';
+  i386_xen_ldflags         = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0';
   x86_64_xen_ldflags       = '$(TARGET_IMG_LDFLAGS)';
   x86_64_xen_ldflags       = '$(TARGET_IMG_BASE_LDOPT),0';
   i386_xen_pvh_ldflags     = '$(TARGET_IMG_LDFLAGS)';
-  i386_xen_pvh_ldflags     = '$(TARGET_IMG_BASE_LDOPT),0x100000';
+  i386_xen_pvh_ldflags     = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x100000';
 
   mips_loongson_ldflags    = '-Wl,-Ttext,0x80200000';
   powerpc_ieee1275_ldflags = '-Wl,-Ttext,0x200000';

@@ -450,10 +451,10 @@ image = {
   sparc64_ieee1275 = boot/sparc64/ieee1275/boot.S;
 
   i386_pc_ldflags = '$(TARGET_IMG_LDFLAGS)';
-  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT),0x7C00';
+  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x7C00';
 
   i386_qemu_ldflags = '$(TARGET_IMG_LDFLAGS)';
-  i386_qemu_ldflags = '$(TARGET_IMG_BASE_LDOPT),$(GRUB_BOOT_MACHINE_LINK_ADDR)';
+  i386_qemu_ldflags = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)$(GRUB_BOOT_MACHINE_LINK_ADDR)';
   i386_qemu_ccasflags = '-DGRUB_BOOT_MACHINE_LINK_ADDR=$(GRUB_BOOT_MACHINE_LINK_ADDR)';
 
   /* The entry point for a.out binaries on sparc64 starts

@@ -478,7 +479,7 @@ image = {
   cppflags = '-DHYBRID_BOOT=1';
 
   i386_pc_ldflags = '$(TARGET_IMG_LDFLAGS)';
-  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT),0x7C00';
+  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x7C00';
 
   objcopyflags = '-O binary';
   enable = i386_pc;

@@ -489,7 +490,7 @@ image = {
 
   i386_pc = boot/i386/pc/cdboot.S;
   i386_pc_ldflags = '$(TARGET_IMG_LDFLAGS)';
-  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT),0x7C00';
+  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x7C00';
 
   sparc64_ieee1275 = boot/sparc64/ieee1275/boot.S;
 

@@ -509,7 +510,7 @@ image = {
   i386_pc = boot/i386/pc/pxeboot.S;
 
   i386_pc_ldflags = '$(TARGET_IMG_LDFLAGS)';
-  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT),0x7C00';
+  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x7C00';
 
   objcopyflags = '-O binary';
   enable = i386_pc;

@@ -520,7 +521,7 @@ image = {
   i386_pc = boot/i386/pc/diskboot.S;
 
   i386_pc_ldflags = '$(TARGET_IMG_LDFLAGS)';
-  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT),0x8000';
+  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x8000';
 
   sparc64_ieee1275 = boot/sparc64/ieee1275/diskboot.S;
   sparc64_ieee1275_ldflags = '-Wl,-Ttext=0x4200';

@@ -536,7 +537,7 @@ image = {
   i386_pc = boot/i386/pc/lnxboot.S;
 
   i386_pc_ldflags = '$(TARGET_IMG_LDFLAGS)';
-  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT),0x6000';
+  i386_pc_ldflags = '$(TARGET_IMG_BASE_LDOPT)$(TARGET_IMG_BASE_LDOPT_ARG_SEP)0x6000';
 
   objcopyflags = '-O binary';
   enable = i386_pc;

This reverts commit ac042f3f58d33ce9cd5ff61750f06da1a1d7b0eb.

Signed-off-by Nicholas Vinson <[email protected]>

---
 configure.ac | 5 -----
 1 file changed, 5 deletions(-)

configure.ac +0 -2

index 2827ae2c1..dfef2e278 100644
@@ -1792,11 +1792,6 @@ LIBS=""
 # Defined in acinclude.m4.
 grub_ASM_USCORE
 grub_PROG_TARGET_CC
-
-# The error message produced by autoconf if autoconf-archive is not

installed is
-# quite misleading and not very helpful. So, try point people in the right direction.
-m4_ifndef([AX_CHECK_LINK_FLAG], [m4_fatal([autoconf-archive is missing. You must install it to generate the configure script.])])
-
if test "x$TARGET_APPLE_LINKER" != x1 ; then AX_CHECK_LINK_FLAG([-Wl,--image-base,0x400000],

     [TARGET_IMG_BASE_LDOPT="-Wl,--image-base"],

--
2.53.0

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Can you explain why?

Regards
Vladimir 'phcoder' Serbinenko

Le sam. 14 févr. 2026, 04:06, Nicholas Vinson <[email protected] <mailto:[email protected]>> a écrit :

    This reverts commit ac042f3f58d33ce9cd5ff61750f06da1a1d7b0eb.

    Signed-off-by: Nicholas Vinson <[email protected]
    <mailto:[email protected]>>
    ---
    configure.ac <http://configure.ac> | 5 -----
      1 file changed, 5 deletions(-)

    diff --git a/configure.ac <http://configure.ac> b/configure.ac
    <http://configure.ac>
    index 2827ae2c1..dfef2e278 100644
    --- a/configure.ac <http://configure.ac>
    +++ b/configure.ac <http://configure.ac>
    @@ -1792,11 +1792,6 @@ LIBS=""
      # Defined in acinclude.m4.
      grub_ASM_USCORE
      grub_PROG_TARGET_CC
    -
    -# The error message produced by autoconf if autoconf-archive is not
    installed is
    -# quite misleading and not very helpful. So, try point people in
    the right direction.
    -m4_ifndef([AX_CHECK_LINK_FLAG], [m4_fatal([autoconf-archive is
    missing. You must install it to generate the configure script.])])
    -
      if test "x$TARGET_APPLE_LINKER" != x1 ; then
      AX_CHECK_LINK_FLAG([-Wl,--image-base,0x400000],
          [TARGET_IMG_BASE_LDOPT="-Wl,--image-base"],
    -- 
    2.53.0


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    https://lists.gnu.org/mailman/listinfo/grub-devel <https://
    lists.gnu.org/mailman/listinfo/grub-devel>

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The i386-pc target now uses a linker script, so -Ttext is no longer required.

Signed-off-by Nicholas Vinson <[email protected]>

---
  acinclude.m4 | 13 ++++++++++++-
  configure.ac | 29 ++++++++++++++++++++++++++---
  2 files changed, 38 insertions(+), 4 deletions(-)

acinclude.m4 +12 -1

index fa7840f09..478aab6d3 100644
@@ -93,7 +93,18 @@ else
  fi
  grub_cv_prog_objcopy_absolute=yes
  for link_addr in 0x2000 0x8000 0x7C00; do
-  if AC_TRY_COMMAND([${CC-cc} ${TARGET_CFLAGS} ${TARGET_LDFLAGS} -nostdlib ${TARGET_IMG_LDFLAGS_AC} ${TARGET_IMG_BASE_LDOPT},$link_addr conftest.o -o conftest.exec]); then :
+
+  target_img_base_ld="${TARGET_IMG_BASE_LDOPT}"
+  case "$target_img_base_ld" in
+    *_grub_text_base)
+      target_img_base_ld="${target_img_base_ld}=$link_addr"
+    ;;
+    *)
+      target_img_base_ld="${target_img_base_ld},$link_addr"
+    ;;
+  esac
+
+  if AC_TRY_COMMAND([${CC-cc} ${TARGET_CFLAGS} ${TARGET_LDFLAGS} -nostdlib ${TARGET_IMG_LDFLAGS_AC} ${target_img_base_ld} conftest.o -o conftest.exec]); then :
    else
      AC_MSG_ERROR([${CC-cc} cannot link at address $link_addr])
    fi

configure.ac +1 -0

index 3106bb11d..4febd084d 100644
@@ -1454,6 +1454,7 @@ if test x$grub_cv_target_cc_link_format = x-arch,i386 || test x$grub_cv_target_c
     TARGET_IMG_LDFLAGS='-nostdlib -static -Wl,-preload -Wl,-segalign,20'
     TARGET_IMG_LDFLAGS_AC='-nostdlib -static -Wl,-preload -Wl,-segalign,20'
     TARGET_IMG_BASE_LDOPT="-Wl,-image_base"
+   TARGET_IMG_BASE_LDOPT_ARG_SEP=","
     TARGET_LDFLAGS_OLDMAGIC=""
  elif test x$grub_cv_target_cc_link_format = x-mi386pe || test x$grub_cv_target_cc_link_format = x-mi386pep ; then
    TARGET_APPLE_LINKER=0

configure.ac +23 -2

+  TARGET_IMG_BASE_LDOPT_ARG_SEP=","
    TARGET_IMG_CFLAGS=
  else
    TARGET_APPLE_LINKER=0

@@ -1469,7 +1471,16 @@ else
    TARGET_IMG_LDSCRIPT=
    TARGET_IMG_LDFLAGS='-Wl,-N'
    TARGET_IMG_LDFLAGS_AC='-Wl,-N'
-  TARGET_IMG_BASE_LDOPT="-Wl,-Ttext"
+  if test "x$target_cpu-$platform" != "xi386-pc"; then
+    TARGET_IMG_BASE_LDOPT="-Wl,-Ttext"
+    TARGET_IMG_BASE_LDOPT_ARG_SEP=","
+  else
+    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${TARGET_IMG_LDSCRIPT}"
+    TARGET_IMG_LDFLAGS_AC="-Wl,-T${srcdir}/conf/i386-pc-kernel.lds"
+  fi
    TARGET_IMG_CFLAGS=
  fi
 

@@ -1802,7 +1813,18 @@ if test "x$target_cpu" = xi386; then
    if test "$platform" != emu && test "x$TARGET_APPLE_LINKER" != x1 ; then
      if test ! -z "$TARGET_IMG_LDSCRIPT"; then
        # Check symbols provided by linker script.
-      CFLAGS="$TARGET_CFLAGS -nostdlib ${TARGET_IMG_LDFLAGS_AC} ${TARGET_IMG_BASE_LDOPT},0x8000"
+      target_img_base_ld="${TARGET_IMG_BASE_LDOPT}"
+      case "$target_img_base_ld" in
+        *_grub_text_base)
+          target_img_base_ld="${target_img_base_ld}="
+        ;;
+        *)
+          target_img_base_ld="${target_img_base_ld},"
+        ;;
+      esac
+      target_img_base_ld="${target_img_base_ld}0x8000"
+      CFLAGS="$TARGET_CFLAGS -nostdlib ${TARGET_IMG_LDFLAGS_AC} ${target_img_base_ld}"
+      target_img_base_ld=""
      fi
      grub_CHECK_BSS_START_SYMBOL
      grub_CHECK_END_SYMBOL

This patch updates conf/i386-cygwin-img.lds to use the _grub_text_base symbol just like conf/i386-pc-kernel.lds. It also updates configure.ac to account for this change.

Signed-off-by Nicholas Vinson <[email protected]>

---
  conf/i386-cygwin-img.lds | 1 +
  configure.ac             | 4 ++--
  2 files changed, 3 insertions(+), 2 deletions(-)

conf/i386-cygwin-img.lds +1 -0

index 578da91b0..26935ce92 100644
@@ -2,6 +2,7 @@
 
  SECTIONS
  {
+  . = _grub_image_base;
    .text :
    {
      start = . ;

configure.ac +0 -0

index 94218e014..6367afddc 100644

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:

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