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From: Peter Maydell <peter.maydell@linaro.org>
To: "Philippe Mathieu-Daudé" <philmd@linaro.org>
Cc: qemu-devel@nongnu.org,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"Dapeng Mi" <dapeng1.mi@intel.com>,
	"Sean Christopherson" <seanjc@google.com>,
	"Bin Meng" <bin.meng@windriver.com>,
	"Zhuocheng Ding" <zhuocheng.ding@intel.com>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"Zhenyu Wang" <zhenyu.z.wang@intel.com>,
	qemu-riscv@nongnu.org,
	"Alistair Francis" <alistair.francis@wdc.com>,
	"Zhao Liu" <zhao1.liu@intel.com>,
	"Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Marcel Apfelbaum" <marcel.apfelbaum@gmail.com>,
	"Robert Hoo" <robert.hu@linux.intel.com>,
	"Yanan Wang" <wangyanan55@huawei.com>,
	qemu-arm@nongnu.org, "Palmer Dabbelt" <palmer@dabbelt.com>,
	"Like Xu" <like.xu.linux@gmail.com>,
	"Alistair Francis" <alistair@alistair23.me>,
	"Zhao Liu" <zhao1.liu@linux.intel.com>,
	"Eduardo Habkost" <eduardo@habkost.net>
Subject: Re: [PATCH 3/5] hw/cpu/cluster: Restrict CPU cluster to a particular CPU type
Date: Tue, 21 Feb 2023 17:59:06 +0000	[thread overview]
Message-ID: <CAFEAcA8vMWOcuRib5aL=SVrRoDMOBdD+PpSOrsZh0kdCU7KavQ@mail.gmail.com> (raw)
In-Reply-To: <20230216142338.82982-4-philmd@linaro.org>

On Thu, 16 Feb 2023 at 14:23, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> CPU cluster id is used by TCG accelerator to "group" CPUs
> sharing the same ISA features, so TranslationBlock can be
> shared between the cluster (see commit f7b78602fd "accel/tcg:
> Add cluster number to TCG TB hash"). This mean we shouldn't
> mix different kind of CPUs into the same cluster.
>
> Enforce that by adding a 'cpu-type' property. The cluster's
> realize() method will check all children are of that 'cpu-type'
> class.
>
> If the property is not set, the first CPU added to a cluster
> sets its CPU type, and only that type fo CPU can be added.

This seems like a reasonable extra assertion to add.
It won't catch all accidental "wrong thing put into
cluster" bugs (you can still put two differently
configured CPUs of the same type in a cluster) but it's
better than nothing.

Personally I think I would just have the "check they're
all the same type" guard, rather than having the board
code set a property explicitly.

thanks
-- PMM


  reply	other threads:[~2023-02-21 17:59 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-16 14:23 [PATCH 0/5] hw/cpu/cluster: Restrict CPU cluster to a particular CPU type Philippe Mathieu-Daudé
2023-02-16 14:23 ` [PATCH 1/5] hw/cpu: Extend CPUState::cluster_index documentation Philippe Mathieu-Daudé
2023-02-21 17:47   ` Peter Maydell
2023-02-16 14:23 ` [PATCH 2/5] hw/cpu/cluster: Only add CPU objects to CPU cluster Philippe Mathieu-Daudé
2023-02-21 17:56   ` Peter Maydell
2023-02-16 14:23 ` [PATCH 3/5] hw/cpu/cluster: Restrict CPU cluster to a particular CPU type Philippe Mathieu-Daudé
2023-02-21 17:59   ` Peter Maydell [this message]
2023-02-16 14:23 ` [PATCH 4/5] hw/arm: Restrict CPU clusters to the expected type Philippe Mathieu-Daudé
2023-02-16 14:23 ` [PATCH 5/5] hw/riscv: " Philippe Mathieu-Daudé

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