Re: [Qemu-devel] [Qemu-arm] [PATCH for-2.13 3/4] arm: always start from first_cpu when registering loader cpu reset callback

[Peter Maydell]

On 12 April 2018 at 17:40, Igor Mammedov <address@hidden> wrote:
> if arm_load_kernel() were passed non first_cpu, QEMU would end up
> with partially set do_cpu_reset() callback leaving some CPUs without it.
>
> Make sure that do_cpu_reset() is registered for all CPUs by enumerating
> CPUs from first_cpu.
>
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
>  hw/arm/boot.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index 2f464ca..2591fee 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -1188,7 +1188,7 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info 
> *info)
>       * actually loading a kernel, the handler is also responsible for
>       * arranging that we start it correctly.
>       */
> -    for (cs = CPU(cpu); cs; cs = CPU_NEXT(cs)) {
> +    for (cs = first_cpu; cs; cs = CPU_NEXT(cs)) {
>          qemu_register_reset(do_cpu_reset, ARM_CPU(cs));
>      }
>  }

Definitely a bug fix, so:
Reviewed-by: Peter Maydell <address@hidden>

I think though that in at least some cases we'll still mishandle
being passed anything other than first_cpu as the CPU pointer,
because in do_cpu_reset() we do some checks for "do this if
cs == first_cpu", on the assumption that first_cpu is the
primary CPU that we're booting. We should instead I suppose
be checking against the CPU pointer we're given as the
arm_load_kernel() argument (which I think do_cpu_reset() can
get at via info->load_kernel_notifier.cpu).

We should probably analyse which boards actually pass anything
other than first_cpu -- I suspect it will end up just being
the xilinx board which has both A and R profile cores...

thanks
-- PMM