> java -jar sigar.jar
sigar> free
total used free
Mem: 28311552 -38588052 66899604
-/+ buffers/cache: -43586117 71897669
Swap: 41943040 13079036 28864004
RAM: 27648MB
sigar> sysinfo
Sigar version.......java=1.6.5.132, native=1.6.5.127
Build date..........java=05/20/2010 04:04 AM, native=05/20/2010 04:06 AM
SCM rev.............java=ef5317a, native=ef5317a
Archlib.............libsigar-amd64-solaris.so
OS description......Solaris 10
OS name.............Solaris
OS arch.............i386
OS machine..........i86pc
OS version..........5.10
OS patch level......unknown
OS vendor...........Sun Microsystems
OS vendor version...10
OS code name........
OS data model.......64
OS cpu endian.......little
Java vm version.....25.66-b17
Java vm vendor......Oracle Corporation
Java home.........../opt/fortune/local/i386/SunOS-5.10/jdk1.8.0_66/jre
SIGAR --- org.hyperic.sigar.Sigar@4b67cf4d
HOST MEM --- Mem: 28311552K av, -38637528K used, 66949080K free
So it looks like Sigar on Solaris 10 (Intel CPU, 64 bit) reports negative memory usage.