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On 11 May 2014 07:27, Luis Machado<lgustavo@codesourcery.com <mailto:lgustavo@codesourcery.com>>wrote: On 05/10/2014 06:56 PM, Sofia wrote: I'm writing my GDB stub and trying to set breakpoints on different threads. When I don't ask GDB about the number of threads, It works fine as a single- threaded application and breakpoints are set correctly. But when I enter - 'info threads', something strange happens. Firstly, GDB reads the contents of all threads' registers(it's OK). Then I enter 'continue' and see that breakpoints are not set at all threads my program has. I don't understand why, but the packet Z0(breakpoint packet) is only sent to inactive thread. The documentation says that if the thread id is not specified, breakpoints will be set at all threads. What's wrong with this or where can I read about such GDB behavior? Is this a software breakpoint (Z0/z0) or a hardware breakpoint we are talking about? A software breakpoint should be valid for all threads if the threads are executing a shared piece of code. If these breakpoints are not triggering, we may have a bug somewhere. For hardware breakpoints, the target code (in this case, the remote stub) is responsible for replicating the hardware breakpoint settings (register contents) to all threads upon their creation. What version of GDB are you using? No, It's a software breakpoint. I set it as [b *addr]. My gdb-multiarch version is GNU gdb (Ubuntu 7.7-0ubuntu3) 7.7 How is breakpoints' setting implemented in gdb? I expect gdb to switch between all currently active threads and send (Z0, addr) packet to all of them. And it definitely doesn't do what I expect. So, how gdb should behave in such cases? I attach my logs(packets and responses of gdbstub and gdb-client), maybe they will better explain what is going on. I divided it into several parts for easier navigation. 1. INITIALIZATION 2. AFTER INFO THREADS COMMAND 3. CONTINUE 4. CTRL+C IN GDB 5. b *0xbff77660 6. CONTINUE AFTER BREAKPOINT SETTING Thank you. -- Sincerely, Sophia Rodina rodina@parallels.mipt.ru
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