On 22 April 2013 13:31, Muhammad Nouman <nouman...@gmail.com> wrote: > Hi ! I am trying to emulate cavium octeon's mips64 linux kernel on Qemu.When > the fork system call is generated from usermode (i.e from init code), after > creating a new thread, the kernel gets a fatal signal from the new thread > and then the new thread never runs. > > I have tried to debug this new thread but the gdb is always showing a single > thread when the "info threads" command is run.It is not showing the other > threads.
When you connect a gdb to QEMU's system emulation, you should not expect to be able to see different user mode processes or threads: you just see the state of the physical CPU (which may be running kernel code or user code, depending). This is similar to the view you get if you connect a debugger to a JTAG port on real hardware. Note that "the kernel gets a fatal signal from the new thread" is backwards -- the kernel sends signals to threads, not the other way around. You should probably try to identify why the kernel thinks it should be sending a signal to this new thread (probably provoked by a hardware exception) and work backwards to figure out why the hardware exception has occurred. PS: the fork system call creates new processes, not new threads (the latter is done via clone). -- PMM
