https://github.com/elogind/elogind/pull/231, but made minimal.
From: Wu Xiaotian <wuxiaotian@loongson.cn>
Date: Tue, 1 Sep 2020 12:13:18 +0800
Subject: [PATCH] architecture: Add support for the LoongArch architecture

(cherry picked from commit 5c0968a2d14d5e1afb40a36c55d3f89805712904)
[resolved merge conflict for minimal diff, also use __loongarch_lp64
instead of __loongarch64 -- xen0n]

basic: update the Arch tuples for LoongArch

(cherry picked from commit 017228934833d8618774353dcccbc5ec9f78ce98)
--- a/src/basic/architecture.h
+++ b/src/basic/architecture.h
@@ -44,6 +44,7 @@ enum {
         ARCHITECTURE_RISCV64,
         ARCHITECTURE_ARC,
         ARCHITECTURE_ARC_BE,
+        ARCHITECTURE_LOONGARCH64,
         _ARCHITECTURE_MAX,
         _ARCHITECTURE_INVALID = -1
 };
@@ -200,6 +201,17 @@ int uname_architecture(void);
 #  elif defined(__SH4A__)
 #    define LIB_ARCH_TUPLE "sh4a-linux-gnu"
 #  endif
+#elif defined(__loongarch_lp64)
+#  define native_architecture() ARCHITECTURE_LOONGARCH64
+#  if defined(__loongarch_double_float)
+#    define LIB_ARCH_TUPLE "loongarch64-linux-gnuf64"
+#  elif defined(__loongarch_single_float)
+#    define LIB_ARCH_TUPLE "loongarch64-linux-gnuf32"
+#  elif defined(__loongarch_soft_float)
+#    define LIB_ARCH_TUPLE "loongarch64-linux-gnusf"
+#  else
+#    error "Unrecognized loongarch architecture variant"
+#  endif
 #elif defined(__m68k__)
 #  define native_architecture() ARCHITECTURE_M68K
 #  define LIB_ARCH_TUPLE "m68k-linux-gnu"