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.

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From: Devel <devel-bounces@sel4.systems> on behalf of Jiusheng Liu <liujiusheng@gmail.com>
Sent: Wednesday, 27 November 2019 1:51 PM
To: devel@sel4.systems <devel@sel4.systems>
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.