Hi Peter,
On 1/21/19 7:43 PM, Peter Maydell wrote:
> If we aren't going to create any RPUs, then don't create the
> rpu-cluster unit. This allows us to add an assertion to the
> cluster object that it contains at least one CPU, which helps
> to avoid bugs in creating clusters and putting CPUs in them.
>
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> ---
> This is a preparatory patch that is necessary for the series
> "[PATCH v3 0/4] tcg: support heterogenous CPU clusters"
> (20190121152218.9592-1-peter.mayd...@linaro.org)
> in order to avoid the xlnx-zcu102 board asserting if started with
> fewer than 5 CPUs.
>
> hw/arm/xlnx-zynqmp.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/hw/arm/xlnx-zynqmp.c b/hw/arm/xlnx-zynqmp.c
> index 370b0e44a38..16cba433cb7 100644
> --- a/hw/arm/xlnx-zynqmp.c
> +++ b/hw/arm/xlnx-zynqmp.c
> @@ -178,6 +178,11 @@ static void xlnx_zynqmp_create_rpu(XlnxZynqMPState *s,
> const char *boot_cpu,
> int i;
> int num_rpus = MIN(smp_cpus - XLNX_ZYNQMP_NUM_APU_CPUS,
> XLNX_ZYNQMP_NUM_RPU_CPUS);
Not related to this patch, but this check seems dangerous, i.e. using
"-smp 2" we get num_rpus=-2 which luckyly doesn't enter the for() loop.
>
> + if (num_rpus == 0) {
With the current codebase, you'd have to check for "num_rpus <= 0", ...
> + /* Don't create rpu-cluster object if there's nothing to put in it */
> + return;
> + }
> +
> object_initialize_child(OBJECT(s), "rpu-cluster", &s->rpu_cluster,
> sizeof(s->rpu_cluster), TYPE_CPU_CLUSTER,
> &error_abort, NULL);
>
... because the rpu cluster is still created:
aarch64-softmmu/qemu-system-aarch64 -M xlnx-zcu102 -smp 2 -S -monitor stdio
(qemu) info qom-tree
/machine (xlnx-zcu102-machine)
/peripheral (container)
/soc (xlnx,zynqmp)
/rpu-cluster (cpu-cluster)
/apu-cluster (cpu-cluster)
/apu-cpu[1] (cortex-a53-arm-cpu)
/unnamed-gpio-in[1] (irq)
/unnamed-gpio-in[3] (irq)
/unnamed-gpio-in[2] (irq)
/unnamed-gpio-in[0] (irq)
/apu-cpu[0] (cortex-a53-arm-cpu)
/unnamed-gpio-in[1] (irq)
/unnamed-gpio-in[3] (irq)
/unnamed-gpio-in[2] (irq)
/unnamed-gpio-in[0] (irq)
What about this instead?
-- >8 --
@@ -451,10 +451,12 @@ static void xlnx_zynqmp_realize(DeviceState *dev,
Error **errp)
"RPUs just use -smp 6.");
}
- xlnx_zynqmp_create_rpu(s, boot_cpu, &err);
- if (err) {
- error_propagate(errp, err);
- return;
+ if (smp_cpus > XLNX_ZYNQMP_NUM_APU_CPUS) {
+ xlnx_zynqmp_create_rpu(s, boot_cpu, &err);
+ if (err) {
+ error_propagate(errp, err);
+ return;
+ }
}
if (!s->boot_cpu_ptr) {
---
Regards,
Phil.
