add powerpc64 and s390x to list of supported archs in INSTALL file
diff --git a/INSTALL b/INSTALL
index 526c3f6..a2a142b 100644
--- a/INSTALL
+++ b/INSTALL
@@ -69,12 +69,20 @@
that does not use FPU registers or instructions is available
* PowerPC
- * Only 32-bit is supported
* Compiler toolchain must provide 64-bit long double, not IBM
double-double or IEEE quad
* For dynamic linking, compiler toolchain must be configured for
"secure PLT" variant
+* PowerPC64
+ * Both little and big endian variants are supported
+ * Compiler toolchain must provide 64-bit long double, not IBM
+ double-double or IEEE quad
+ * Compiler toolchain must use the new (ELFv2) ABI regardless of
+ whether it is for little or big endian
+
+* S390X (64-bit S390)
+
* SuperH (SH)
* Standard ELF ABI or FDPIC ABI (shared-text without MMU)
* Little-endian by default; big-engian variant also supported