Re: [RFC PATCH v3 4/9] hw/arm/virt: Initialize the present cpu members

[wangyanan (Y)]

Hi Salil,

On 2021/5/18 4:48, Salil Mehta wrote:
> > From: Qemu-arm [mailto:qemu-arm-bounces+salil.mehta=huawei.com@nongnu.org]
> > On Behalf Of Yanan Wang
> > Sent: Sunday, May 16, 2021 11:29 AM
> > To: Peter Maydell <peter.maydell@linaro.org>; Andrew Jones
> > <drjones@redhat.com>; Michael S . Tsirkin <mst@redhat.com>; Igor Mammedov
> > <imammedo@redhat.com>; Shannon Zhao <shannon.zhaosl@gmail.com>; Alistair
> > Francis <alistair.francis@wdc.com>; David Gibson
> > <david@gibson.dropbear.id.au>; qemu-devel@nongnu.org; qemu-arm@nongnu.org
> > Cc: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>; zhukeqian
> > <zhukeqian1@huawei.com>; yangyicong <yangyicong@huawei.com>; Zengtao (B)
> > <prime.zeng@hisilicon.com>; Wanghaibin (D) <wanghaibin.wang@huawei.com>;
> > yuzenghui <yuzenghui@huawei.com>; Paolo Bonzini <pbonzini@redhat.com>;
> > Philippe Mathieu-Daudé <philmd@redhat.com>
> > Subject: [RFC PATCH v3 4/9] hw/arm/virt: Initialize the present cpu members
> >
> > We create and initialize a cpuobj for each present cpu in
> > machvirt_init(). Now we also initialize the cpu member of
> > structure CPUArchId for each present cpu in the function.
> [...]
>
> >           qdev_realize(DEVICE(cpuobj), NULL, &error_fatal);
> > +
> > +        /*
> > +         * As ARM cpu hotplug is not supported yet, we initialize
> > +         * the present cpu members here.
> > +         */
> > +        machine->possible_cpus->cpus[n].cpu = cpuobj;
>
> when vcpu Hotplug is not supported yet, what necessitates this change now?
The initialization will gives a way to determine whether a CPU is 
present or not.
At least, for now it will be used when generating ACPI tables, e.g. 
DSDT, MADT.
See patch 5 and 6.

Thanks,
Yanan
> .