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Re: [PATCH] hw/arm/xlnx-zynqmp: fix unsigned error when checking the RPU
From: |
Clément Chigot |
Subject: |
Re: [PATCH] hw/arm/xlnx-zynqmp: fix unsigned error when checking the RPUs number |
Date: |
Wed, 24 May 2023 17:17:40 +0200 |
On Wed, May 24, 2023 at 5:06 PM Philippe Mathieu-Daudé
<philmd@linaro.org> wrote:
>
> Hi Clément,
>
> On 24/5/23 16:37, Clément Chigot wrote:
> > When passing --smp with a number lower than XLNX_ZYNQMP_NUM_APU_CPUS,
> > the expression (ms->smp.cpus - XLNX_ZYNQMP_NUM_APU_CPUS) will result
> > in a positive number as ms->smp.cpus is a unsigned int.
> > This will raise the following error afterwards, as Qemu will try to
> > instantiate some additional RPUs.
> > | $ qemu-system-aarch64 --smp 1 -M xlnx-zcu102
> > | **
> > | ERROR:../src/tcg/tcg.c:777:tcg_register_thread:
> > | assertion failed: (n < tcg_max_ctxs)
> >
> > Signed-off-by: Clément Chigot <chigot@adacore.com>
> > ---
> > hw/arm/xlnx-zynqmp.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/hw/arm/xlnx-zynqmp.c b/hw/arm/xlnx-zynqmp.c
> > index 335cfc417d..5905a33015 100644
> > --- a/hw/arm/xlnx-zynqmp.c
> > +++ b/hw/arm/xlnx-zynqmp.c
> > @@ -213,7 +213,7 @@ static void xlnx_zynqmp_create_rpu(MachineState *ms,
> > XlnxZynqMPState *s,
> > const char *boot_cpu, Error **errp)
> > {
> > int i;
> > - int num_rpus = MIN(ms->smp.cpus - XLNX_ZYNQMP_NUM_APU_CPUS,
> > + int num_rpus = MIN((int)(ms->smp.cpus - XLNX_ZYNQMP_NUM_APU_CPUS),
> > XLNX_ZYNQMP_NUM_RPU_CPUS);
> >
> > if (num_rpus <= 0) {
>
> Can we set mc->min_cpus in xlnx_zcu102_machine_class_init() instead?
>
> -- >8 --
> diff --git a/hw/arm/xlnx-zcu102.c b/hw/arm/xlnx-zcu102.c
> index 4c84bb932a..60a2710e21 100644
> --- a/hw/arm/xlnx-zcu102.c
> +++ b/hw/arm/xlnx-zcu102.c
> @@ -269,6 +269,7 @@ static void
> xlnx_zcu102_machine_class_init(ObjectClass *oc, void *data)
> mc->block_default_type = IF_IDE;
> mc->units_per_default_bus = 1;
> mc->ignore_memory_transaction_failures = true;
> + mc->min_cpus = XLNX_ZYNQMP_NUM_APU_CPUS;
> mc->max_cpus = XLNX_ZYNQMP_NUM_APU_CPUS + XLNX_ZYNQMP_NUM_RPU_CPUS;
> mc->default_cpus = XLNX_ZYNQMP_NUM_APU_CPUS;
> mc->default_ram_id = "ddr-ram";
> ---
>
> $ qemu-system-aarch64 -M xlnx-zcu102 -smp 1
> qemu-system-aarch64: Invalid SMP CPUs 1. The min CPUs supported by
> machine 'xlnx-zcu102' is 4
We encountered this issue when we were trying to emulate a zynqmp with
only two cortex-a53 cores. I don't have the full context but this was
probably to debug a race condition or something like that.
Thus, I would like to keep the possibility of lowering the CPU number,
even if it doesn't match the real board.
Clément