Re: [PATCH v2 1/2] arm64: dts: broadcom: bcmbca: bcm4908: Reserve CFE stub area

[Florian Fainelli]

From: Florian Fainelli <f.fainelli@xxxxxxxxx>

On Fri,  4 Oct 2024 22:01:54 -0700, Sam Edwards <cfsworks@xxxxxxxxx> wrote:
> The CFE bootloader places a stub program in the first page of physical
> memory to hold the secondary CPUs until the boot CPU writes the release
> address, but does not splice a /reserved-memory node into the FDT to
> protect it. 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. Ideally, there would be some hypothetical mechanism
> we could use to indicate that this area of memory is sensitive only
> during boot. But as there is none, and 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 the
> first 4KiB of physical memory.
> 
> Signed-off-by: Sam Edwards <CFSworks@xxxxxxxxx>
> ---

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