From dfb5e954a04f59b0456cc4c0ddf3acaf22e0ff07 Mon Sep 17 00:00:00 2001
From: Richard W.M. Jones <rjones@redhat.com>
Date: Feb 28 2021 20:45:47 +0000
Subject: Workaround for glibc non-constant SIGSTKSZ


https://github.com/ocaml/ocaml/issues/10250

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>

---

diff --git a/runtime/signals_nat.c b/runtime/signals_nat.c
index 8b64ab4..7f0a975 100644
--- a/runtime/signals_nat.c
+++ b/runtime/signals_nat.c
@@ -181,7 +181,19 @@ DECLARE_SIGNAL_HANDLER(trap_handler)
 #error "CONTEXT_SP is required if HAS_STACK_OVERFLOW_DETECTION is defined"
 #endif
 
+#ifndef __GLIBC__
 static char sig_alt_stack[SIGSTKSZ];
+#else
+/* glibc 2.34 has non-constant SIGSTKSZ */
+static char *sig_alt_stack;
+
+static void allocate_sig_alt_stack(void) __attribute__((constructor));
+static void
+allocate_sig_alt_stack(void)
+{
+  sig_alt_stack = malloc(SIGSTKSZ);
+}
+#endif
 
 /* Code compiled with ocamlopt never accesses more than
    EXTRA_STACK bytes below the stack pointer. */