The target architecture is set to "i386". 0x0000fff0 in ?? () Hardware assisted breakpoint 1 at 0x106bd5: file kernel/syscall.c, line 123. Breakpoint 1, syscall_dispatch (frame=0x12efb4) at kernel/syscall.c:123 123 KASSERT((frame->cs & 3) == 3 && frame->vector == 128 && frame->error == 0); PASS: CPL3 int80 used DPL3 interrupt gate; 76-byte frame, post-INT EIP, GPR and saved IF/DF/CF verified Hardware assisted breakpoint 2 at 0x105fa2: file kernel/task.c, line 694. Breakpoint 2, syscall_demo_done () at kernel/task.c:694 694 { __asm__ volatile("" ::: "memory"); } PASS: write/yield, copy-to-user and all return paths verified; bad DPL gate isolated; survivor and page recovery verified Hardware assisted breakpoint 3 at 0x1017fe: file kernel/keyboard.c, line 114. Breakpoint 3, keyboard_ready () at kernel/keyboard.c:114 114 void keyboard_ready(void) { __asm__ volatile("" ::: "memory"); } PASS: syscall demo reaches original blocking keyboard consumer