From: Salil Mehta <salil.mehta@huawei.com>
To: Andrew Jones <drjones@redhat.com>
Cc: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>,
"Peter Maydell" <peter.maydell@linaro.org>,
"linuxarm@openeuler.org" <linuxarm@openeuler.org>,
"Michael S . Tsirkin" <mst@redhat.com>,
"Wanghaibin (D)" <wanghaibin.wang@huawei.com>,
zhukeqian <zhukeqian1@huawei.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
yangyicong <yangyicong@huawei.com>,
"wangyanan (Y)" <wangyanan55@huawei.com>,
"Shannon Zhao" <shannon.zhaosl@gmail.com>,
"qemu-arm@nongnu.org" <qemu-arm@nongnu.org>,
"Alistair Francis" <alistair.francis@wdc.com>,
"Zengtao (B)" <prime.zeng@hisilicon.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
yuzenghui <yuzenghui@huawei.com>,
"Igor Mammedov" <imammedo@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"David Gibson" <david@gibson.dropbear.id.au>
Subject: RE: [RFC PATCH v3 4/9] hw/arm/virt: Initialize the present cpu members
Date: Tue, 18 May 2021 18:50:46 +0000 [thread overview]
Message-ID: <0ff033fa8eac400fade06e6be0a98847@huawei.com> (raw)
In-Reply-To: <20210518075027.wjpdjvoam7dlzign@gator.home>
> From: Andrew Jones [mailto:drjones@redhat.com]
> Sent: Tuesday, May 18, 2021 8:50 AM
>
> On Tue, May 18, 2021 at 07:04:51AM +0000, Salil Mehta wrote:
> > > From: wangyanan (Y)
> > > Sent: Tuesday, May 18, 2021 5:43 AM
> > >
> > > 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.
> >
> > yes, but why do you require it now as part of the vcpu topology change?
> >
> > As-far-as-i-can-see, PPTT table changes(part of patch 5/9) do not require
> > this change. Change in Patch 5/9 has also been done in anticipation of
> > some future requirement(vcpu Hotplug?).
> >
> > Please correct me here if I am wrong?
> >
>
> Hi Salil,
>
> The problem is that we've never required smp.cpus == smp.maxcpus, so
> a user could have smp.cpus < smp.maxcpus. We want the topology to match
> maxcpus, but only enable cpus. However, if you think we should just not
> allow cpus < maxcpus until hot plug is sorted out, then we could discuss
> a way of trying to enforce cpus == maxcpus, but I'm not sure how we can
> without breaking existing command lines.
Hi Andrew,
Ideally, if the vcpu Hotplug is not supported the check in the smp_parse()
should impose (cpus == maxcpus). This as of now is just a warning of invalid
configuration I think. Beside this does not breaks any prior usages which you
suggested might happen?
Again, this is not a blocking issue from my side but just a humble suggestion.
You might want to take a call on this :)
Thanks
Salil.
next prev parent reply other threads:[~2021-05-18 19:10 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-16 10:28 [RFC PATCH v3 0/9] hw/arm/virt: Introduce cpu topology support Yanan Wang
2021-05-16 10:28 ` [RFC PATCH v3 1/9] hw/arm/virt: Disable cpu topology support on older machine types Yanan Wang
2021-05-16 10:28 ` [RFC PATCH v3 2/9] device_tree: Add qemu_fdt_add_path Yanan Wang
2021-05-17 3:11 ` David Gibson
2021-05-17 13:18 ` wangyanan (Y)
2021-05-17 6:27 ` Andrew Jones
2021-05-17 13:21 ` wangyanan (Y)
2021-05-16 10:28 ` [RFC PATCH v3 3/9] hw/arm/virt: Add cpu-map to device tree Yanan Wang
2021-05-17 6:41 ` Andrew Jones
2021-05-17 15:00 ` wangyanan (Y)
2021-05-18 7:46 ` Andrew Jones
2021-05-18 10:50 ` wangyanan (Y)
2021-05-16 10:28 ` [RFC PATCH v3 4/9] hw/arm/virt: Initialize the present cpu members Yanan Wang
2021-05-17 6:43 ` Andrew Jones
2021-05-17 20:48 ` Salil Mehta
2021-05-18 4:42 ` wangyanan (Y)
2021-05-18 7:04 ` Salil Mehta
2021-05-18 7:50 ` Andrew Jones
2021-05-18 18:50 ` Salil Mehta [this message]
2021-05-16 10:28 ` [RFC PATCH v3 5/9] hw/arm/virt-acpi-build: Use possible cpus in generation of DSDT Yanan Wang
2021-05-16 10:28 ` [RFC PATCH v3 6/9] hw/arm/virt-acpi-build: Use possible cpus in generation of MADT Yanan Wang
2021-05-17 7:42 ` Andrew Jones
2021-05-17 16:27 ` wangyanan (Y)
2021-05-18 8:15 ` Andrew Jones
2021-05-18 11:47 ` wangyanan (Y)
2021-05-18 13:40 ` Andrew Jones
2021-05-17 17:07 ` Salil Mehta
2021-05-18 5:02 ` wangyanan (Y)
2021-05-18 6:47 ` Salil Mehta
2021-05-18 11:58 ` wangyanan (Y)
2021-05-16 10:28 ` [RFC PATCH v3 7/9] hw/acpi/aml-build: Add Processor hierarchy node structure Yanan Wang
2021-05-17 7:47 ` Andrew Jones
2021-05-16 10:28 ` [RFC PATCH v3 8/9] hw/arm/virt-acpi-build: Generate PPTT table Yanan Wang
2021-05-17 8:02 ` Andrew Jones
2021-05-17 13:43 ` wangyanan (Y)
2021-05-17 14:45 ` Andrew Jones
2021-05-17 16:02 ` wangyanan (Y)
2021-05-16 10:29 ` [RFC PATCH v3 9/9] hw/arm/virt: Add separate -smp parsing function for ARM machines Yanan Wang
2021-05-17 8:24 ` Andrew Jones
2021-05-18 2:16 ` wangyanan (Y)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=0ff033fa8eac400fade06e6be0a98847@huawei.com \
--to=salil.mehta@huawei.com \
--cc=alistair.francis@wdc.com \
--cc=david@gibson.dropbear.id.au \
--cc=drjones@redhat.com \
--cc=imammedo@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxarm@openeuler.org \
--cc=mst@redhat.com \
--cc=pbonzini@redhat.com \
--cc=peter.maydell@linaro.org \
--cc=philmd@redhat.com \
--cc=prime.zeng@hisilicon.com \
--cc=qemu-arm@nongnu.org \
--cc=qemu-devel@nongnu.org \
--cc=shannon.zhaosl@gmail.com \
--cc=song.bao.hua@hisilicon.com \
--cc=wanghaibin.wang@huawei.com \
--cc=wangyanan55@huawei.com \
--cc=yangyicong@huawei.com \
--cc=yuzenghui@huawei.com \
--cc=zhukeqian1@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).