linux-kernel - Re: [PATCH v2 2/2] arm64: dts: broadcom: bcmbca: bcm4908: Protect cpu-release-addr

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Message-ID: <20241124175647.718610-1-florian.fainelli@broadcom.com>
Date: Sun, 24 Nov 2024 09:56:47 -0800
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: bcm-kernel-feedback-list@...adcom.com,
	Sam Edwards <cfsworks@...il.com>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Rafał Miłecki <rafal@...ecki.pl>,
	William Zhang <william.zhang@...adcom.com>,
	Anand Gore <anand.gore@...adcom.com>,
	Kursad Oney <kursad.oney@...adcom.com>
Cc: Florian Fainelli <f.fainelli@...il.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Sam Edwards <CFSworks@...il.com>
Subject: Re: [PATCH v2 2/2] arm64: dts: broadcom: bcmbca: bcm4908: Protect cpu-release-addr

From: Florian Fainelli <f.fainelli@...il.com>

On Fri,  4 Oct 2024 22:01:55 -0700, Sam Edwards <cfsworks@...il.com> wrote:
> The `cpu-release-addr` property is relevant only when the "spin-table"
> enable method is used. It is the physical address where the bootloader
> expects Linux to write the secondary CPU entry point's physical address.
> On this platform, only the CFE bootloader uses this method: U-Boot uses
> PSCI instead.
> 
> CFE actually walks the FDT to learn this address, so we're free to put
> it wherever we want. We only need to make sure that it goes in a
> reserved-memory block so that writing to it during early boot does not
> risk conflicting with an unrelated memory allocation: this was not done.
> 
> Since the previous patch reserved the first page of memory for CFE's
> secondary-CPU init stub, which is actually much smaller than a page,
> just put this address at the end of that page and it shall be so
> protected.
> 
> Signed-off-by: Sam Edwards <CFSworks@...il.com>
> ---

Applied to https://github.com/Broadcom/stblinux/commits/devicetree-arm64/next, thanks!
--
Florian