HelenOS sources

FS_SIGNATURE       54 kernel/arch/amd64/src/smp/mps.c #define FS_SIGNATURE  UINT32_C(0x5f504d5f)
FS_SIGNATURE       54 kernel/arch/ia32/src/smp/mps.c #define FS_SIGNATURE  UINT32_C(0x5f504d5f)
HelenOS homepage, sources at GitHub