docs/known-issues: add note about build issue on x86_64 with 32bit userspace

Signed-off-by: Johannes Stezenbach <js@sig21.net>

1 files changed, 20 insertions, 0 deletions

diff --git a/docs/B - Known issues.txt b/docs/B - Known issues.txt
index f753ac6..0217b7a 100644
--- a/docs/B - Known issues.txt
+++ b/docs/B - Known issues.txt
@@ -233,3 +233,23 @@ Workaround:
   See above issue.
 
 --------------------------------
+Symptoms:
+  On x86_64 hosts with 32bit userspace the GMP build fails with:
+    configure: error: Oops, mp_limb_t is 32 bits, but the assembler code
+    in this configuration expects 64 bits.
+    You appear to have set $CFLAGS, perhaps you also need to tell GMP the
+    intended ABI, see "ABI and ISA" in the manual.
+
+Explanations:
+  "uname -m" detects x86_64 but the build host is really x86.
+
+Status:
+  CURRENT
+
+Fix:
+  None so far. See above issue.
+
+Workaround:
+  use "setarch i686 ct-ng build"
+
+--------------------------------