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From: Florian Fainelli <florian.fainelli@broadcom.com>
To: "Sam Edwards" <cfsworks@gmail.com>,
	"Rafał Miłecki" <rafal@milecki.pl>,
	"William Zhang" <william.zhang@broadcom.com>,
	"Anand Gore" <anand.gore@broadcom.com>,
	"Kursad Oney" <kursad.oney@broadcom.com>
Cc: Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Broadcom internal kernel review list
	<bcm-kernel-feedback-list@broadcom.com>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: dts: broadcom: bcmbca: bcm4908: Reserve CFE stub area
Date: Thu, 3 Oct 2024 15:41:17 -0700	[thread overview]
Message-ID: <78f25b22-f35b-4183-baec-7ddc0c5e3fda@broadcom.com> (raw)
In-Reply-To: <20241003213007.1339811-1-CFSworks@gmail.com>

On 10/3/24 14:30, Sam Edwards wrote:
> The CFE bootloader places a stub program at 0x0000-0xFFFF to hold the
> secondary CPUs until the boot CPU writes the release address. If Linux
> overwrites this program before execution reaches smp_prepare_cpus(), the
> secondary CPUs may become inaccessible.
> 
> This is only a problem with CFE, and then only until the secondary CPUs
> are brought online. However, since it is such a small amount of memory,
> it is easiest to reserve it unconditionally.
> 
> Therefore, add a /reserved-memory node to bcm4908.dtsi to protect this
> critical memory region.
> 
> Signed-off-by: Sam Edwards <CFSworks@gmail.com>

Not objecting to the solution, but should not this be moved to a 
per-board DTS given that there are boards using CFE, and some using 
u-boot + ARM TF that are unlikely to suffer from that problem?

-- 
Florian

  reply	other threads:[~2024-10-03 22:41 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-03 21:30 Sam Edwards
2024-10-03 22:41 ` Florian Fainelli [this message]
2024-10-04 18:23   ` Sam Edwards
2024-10-04 23:36     ` Florian Fainelli

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