[PATCH] configure: Add -mno-relax on riscv*

[PATCH] configure: Add -mno-relax on riscv*

[Vladimir Serbinenko]

Without this option compiler sometimes emits R_RISCV_ALIGN relocs.
Unlike other relocs this one requires the linker to do NOP deletions
and we can't ignore them. Just instruct compiler not to emit them

Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
---
 configure.ac | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/configure.ac b/configure.ac
index 34f4f9415..2818a73a6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -913,6 +913,31 @@ if test "x$target_cpu" = xloongarch64; then
   TARGET_CCASFLAGS="$TARGET_CCASFLAGS -Wa,-mla-global-with-abs"
 fi
 
+if test "x$target_cpu" = xriscv64 || test "x$target_cpu" = xriscv32; then
+  AC_CACHE_CHECK([for no-relax options], grub_cv_target_cc_mno_relax, [
+    grub_cv_target_cc_mno_relax=no
+    for cand in "-mno-relax" "-Wa,-mno-relax"; do
+      if test x"$grub_cv_target_cc_mno_relax" != xno ; then
+        break
+      fi
+      CFLAGS="$TARGET_CFLAGS $cand -Werror"
+      AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+	    asm (".globl start; start:");
+	    void __main (void);
+	    void __main (void) {}
+	    int main (void);
+	    ]], [[]])], [grub_cv_target_cc_mno_relax="$cand"], [])
+    done
+  ])
+
+  CFLAGS="$TARGET_CFLAGS"
+
+  if test x"$grub_cv_target_cc_mno_relax" != xno ; then
+    TARGET_CFLAGS="$TARGET_CFLAGS $grub_cv_target_cc_mno_relax"
+    TARGET_CCASFLAGS="$TARGET_CCASFLAGS $grub_cv_target_cc_mno_relax"
+  fi
+fi
+
 # GRUB doesn't use float or doubles at all. Yet some toolchains may decide
 # that floats are a good fit to run instead of what's written in the code.
 # Given that floating point unit is disabled (if present to begin with)
-- 
2.49.0


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Re: [PATCH] configure: Add -mno-relax on riscv*

[Daniel Kiper]

On Thu, Mar 27, 2025 at 07:32:23PM +0300, Vladimir Serbinenko wrote:
> Without this option compiler sometimes emits R_RISCV_ALIGN relocs.
> Unlike other relocs this one requires the linker to do NOP deletions
> and we can't ignore them. Just instruct compiler not to emit them
>
> Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

Daniel

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