R0 98 kernel/arch/mips32/src/debug/stacktrace.c ((0x0 << OP_SHIFT) | (SP << RS_SHIFT) | (R0 << RT_SHIFT) | 0x21) R0 100 kernel/arch/mips32/src/debug/stacktrace.c ((0x0 << OP_SHIFT) | (SP << RD_SHIFT) | (R0 << RT_SHIFT) | 0x21)HelenOS homepage, sources at GitHub