https://github.com/ximion/appstream/pull/666

--- AppStream-1.0.3/src/as-system-info.c.orig
+++ AppStream-1.0.3/src/as-system-info.c
@@ -52,6 +52,8 @@
 #elif defined(__FreeBSD__) || defined(__NetBSD__) || defined(__APPLE__)
 #include <sys/types.h>
 #include <sys/sysctl.h>
+#elif defined(__sun)
+#include <unistd.h>
 #endif
 #ifdef HAVE_SYSTEMD
 #include <systemd/sd-hwdb.h>
@@ -498,6 +500,12 @@
 	statex.dwLength = sizeof (statex);
 	GlobalMemoryStatusEx (&statex);
 	return statex.ullTotalPhys / (1024 * 1024);
+#elif defined(__sun)
+	long physpages = sysconf(_SC_PHYS_PAGES);
+	long pagesize = sysconf(_SC_PAGESIZE);
+	if (physpages > 0 && pagesize > 0)
+		return (physpages * pagesize) / MB_IN_BYTES;
+	return 0;
 #else
 #error "Implementation of as_get_physical_memory_total() missing for this OS."
 #endif