Re: [PATCH v4 1/1] hw/arm/sbsa-ref: Enable CPU cluster on ARM sbsa machine

From: "xiongyining1480@phytium.com.cn" <xiongyining1480@phytium.com.cn>
To: "Richard Henderson" <richard.henderson@linaro.org>,
	 qemu-arm <qemu-arm@nongnu.org>,
	qemu-devel <qemu-devel@nongnu.org>
Cc: rad <rad@semihalf.com>, peter.maydell <peter.maydell@linaro.org>,
	 quic_llindhol <quic_llindhol@quicinc.com>,
	 "Marcin Juszkiewicz" <marcin.juszkiewicz@linaro.org>
Subject: Re: [PATCH v4 1/1] hw/arm/sbsa-ref: Enable CPU cluster on ARM sbsa machine
Date: Sun, 28 Apr 2024 10:12:06 +0800	[thread overview]
Message-ID: <2024042810120618268213@phytium.com.cn> (raw)
In-Reply-To: a25e01c0-5f6e-4568-93ec-970987eb6d07@linaro.org

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xiongyining1480@phytium.com.cn

From: Richard Henderson
Date: 2024-04-27 00:06
To: Xiong Yining; qemu-arm; qemu-devel
CC: rad; peter.maydell; quic_llindhol; marcin.juszkiewicz
Subject: Re: [PATCH v4 1/1] hw/arm/sbsa-ref: Enable CPU cluster on ARM sbsa machine
On 4/26/24 00:35, Xiong Yining wrote:
> From: xiongyining1480 <xiongyining1480@phytium.com.cn>
> 
> Enable CPU cluster support on SbsaQemu platform, so that users can
> specify a 4-level CPU hierarchy sockets/clusters/cores/threads. And
> this topology can be passed to the firmware through DT cpu-map.
> 
> Signed-off-by: Xiong Yining <xiongyining1480@phytium.com.cn>
> tested-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
> ---
>   docs/system/arm/sbsa.rst |  4 ++++
>   hw/arm/sbsa-ref.c        | 37 ++++++++++++++++++++++++++++++++++++-
>   2 files changed, 40 insertions(+), 1 deletion(-)

> Isn't this basically what MPIDR_EL1 is supposed to indicate?
> We do not yet implement all of that in QEMU, but should.

> Why does the same info need to be replicated in devicetree?

sbsa uses PPTT to indicate the cpu topology, and OS use the ACPI to get hardware infomation. We add the related information in devicetree, and TF-A parses devicetree
and extract data form it , so EDK2 can gather data form TF-A to create PPTT tables via SMC calls. 

Now the PPTT tables created by EDK2 lose some detailed information, so the cpu topology OS identified cannot align with the qemu configure. We hope to add the topology 
information in device tree, so EKD2 can create more detailed PPTT tables.

> r~

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