gnu: hurd: Add patch to prevent hang of crash-dump-core.

* gnu/packages/patches/hurd-crash-x86_64.patch: New patch.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/hurd.scm (hurd): Add patch.

Change-Id: I4a6b3a3385a9890c4a1781092ad1168a7b51e50f

gnu/local.mk

@@ -1603,6 +1603,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/hubbub-sort-entities.patch		\
   %D%/packages/patches/hueplusplus-mbedtls.patch		\
   %D%/packages/patches/hugs-fix-build.patch			\
+  %D%/packages/patches/hurd-crash-x86_64.patch			\
   %D%/packages/patches/hurd-refcounts-assert.patch		\
   %D%/packages/patches/hurd-rumpdisk-no-hd.patch		\
   %D%/packages/patches/hurd-startup.patch			\

gnu/packages/hurd.scm

@@ -337,7 +337,8 @@ Hurd-minimal package which are needed for both glibc and GCC.")
     (name "hurd")
     (source (origin
               (inherit (package-source hurd-headers))
-              (patches (search-patches "hurd-refcounts-assert.patch"
+              (patches (search-patches "hurd-crash-x86_64.patch"
+                                       "hurd-refcounts-assert.patch"
                                        "hurd-rumpdisk-no-hd.patch"
                                        "hurd-startup.patch"
                                        "hurd-streamio-select.patch"

gnu/packages/patches/hurd-crash-x86_64.patch

@@ -0,0 +1,30 @@
+From c809367cb503830346bfb1d1fd927c09d3f3cb16 Mon Sep 17 00:00:00 2001
+From: Samuel Thibault <samuel.thibault@ens-lyon.org>
+Date: Mon, 16 Feb 2026 00:32:00 +0100
+Subject: crash: Fix hang on x86_64 core generation
+
+The produced core file still make gdb crash, but at least crash doen't
+hang.
+---
+ exec/elfcore.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/exec/elfcore.c b/exec/elfcore.c
+index 8c85b13b..a2360965 100644
+--- a/exec/elfcore.c
++++ b/exec/elfcore.c
+@@ -97,6 +97,11 @@ fetch_thread_fpregset (thread_t thread, prfpregset_t *fpregs)
+   struct i386_float_state st;
+   mach_msg_type_number_t count = i386_FLOAT_STATE_COUNT;
+ 
++  if (!*fpregs)
++    /* FIXME: having a pointer here is bogus actually, prfpregset_t should be a
++       struct, not a pointer, like on i386.  This needs to be fixed in glibc
++       etc.  */
++    return;
+   memset (*fpregs, 0, sizeof (**fpregs));
+ 
+   err = thread_get_state (thread, i386_FLOAT_STATE,
+-- 
+cgit v1.2.3
+