Does it work if you try using hardware breakpoints? The camkes-vm-linux tutorial uses hardware virtualisation via kvm so the software breakpoints likely won't work. Replacing break with hbreak may fix your issue. ------------------------------ *From:* Devel &lt;devel-bounces(a)sel4.systems&gt; on behalf of Jiusheng Liu < liujiusheng(a)gmail.com&gt; *Sent:* Wednesday, 27 November 2019 1:51 PM *To:* devel(a)sel4.systems &lt;devel(a)sel4.systems&gt; *Subject:* [seL4] Userspace debugging with QEMU/gdb Hi, From the page https://docs.sel4.systems/DebuggingGuide.html (section Userspace debugging), I know we can debug userspace process by command below: ---------------------------- cmd example start ---------------------------------------- gdb ./dynamic-2 Reading symbols from ./dynamic-2...done. (gdb) target remote :1234 Remote debugging using :1234 0x000000000000fff0 in ?? () (gdb) break main Breakpoint 1 at 0x402011: file sel4-tutorials-manifest/dynamic-2/main.c, line 161. (gdb) c Continuing. Breakpoint 1, main () at sel4-tutorials-manifest/dynamic-2/main.c:161 161 (gdb) ---------------------------- cmd example end ---------------------------------------- It works for normal userspace process (such as the example code in tutorials: https://docs.sel4.systems/Tutorials/dynamic-2.html ). But when I want to debug the userspace process for the code in the tutorials page https://docs.sel4.systems/Tutorials/camkes-vm-linux.html (one virtual machine in seL4), I cannot catch the breakpoints. So can you help me to explain why I cannot catch the breakpoint? and can we debug the vmm create process with qemu/gdb? Thanks.