Alistair Francis <alistair.fran...@xilinx.com> writes: > On Wed, Jan 31, 2018 at 12:32 PM, Alex Bennée <alex.ben...@linaro.org> wrote: >> >> Alistair Francis <alistair.fran...@xilinx.com> writes: >> >>> On Tue, Jan 30, 2018 at 8:26 PM, Paolo Bonzini <pbonz...@redhat.com> wrote: >>>> On 30/01/2018 18:56, Alistair Francis wrote: >>>>> >>>>> I don't have a good solution though, as setting CPU_INTERRUPT_RESET >>>>> doesn't help (that isn't handled while we are halted) and >>>>> async_run_on_cpu()/run_on_cpu() doesn't reliably reset the CPU when we >>>>> want. >>>>> >>>>> I've ever tried pausing all CPUs before reseting the CPU and them >>>>> resuming them all but that doesn't seem to to work either. >>>> >>>> async_safe_run_on_cpu would be like async_run_on_cpu, except that it >>>> takes care of stopping all other CPUs while the function runs. >>>> >>>>> Is there >>>>> anything I'm missing? Is there no reliable way to reset a CPU? >>>> >>>> What do you mean by reliable? Executing no instruction after the one >>>> you were at? >>> >>> The reset is called by a GPIO line, so I need the reset to be called >>> basically as quickly as the GPIO line changes. The async_ and >>> async_safe_ functions seem to not run quickly enough, even if I run a >>> process_work_queue() function afterwards. >>> >>> Is there a way to kick the CPU to act on the async_*? >> >> Define quickly enough? The async_(safe) functions kick the vCPUs so they >> will all exit the run loop as they enter the next TB (even if they loop >> to themselves). > > We have a special power controller CPU that wakes all the CPUs up and > at boot the async_* functions don't wake the CPUs up. If I just use > the cpu_rest() function directly everything starts fine (but then I > hit issues later). > > If I forcefully run process_queued_cpu_work() then I can get the CPUs > up, but I don't think that is the right solution. > >> >> From an external vCPUs point of view those extra instructions have >> already executed. If the resetting vCPU needs them to have reset by the >> time it executes it's next instruction it should either cpu_loop_exit at >> that point or ensure it is the last instruction in it's TB (which is >> what we do for the MMU flush cases in ARM, they all end the TB at that >> point). > > cpu_loop_exit() sounds like it would help, but as I'm not in the CPU > context it just seg faults.
What context are you in? gdb-stub does have to something like this. > > Alistair > >> >> >>> >>> Thanks, >>> Alistair >>> >>>> >>>> Paolo >>>> >> >> >> -- >> Alex Bennée >> -- Alex Bennée
