From: Florian Fainelli <f.fainelli@gmail.com>
To: Phil Elwell <phil@raspberrypi.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Russell King <linux@armlinux.org.uk>,
Florian Fainelli <f.fainelli@gmail.com>,
bcm-kernel-feedback-list@broadcom.com,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
linux-rpi-kernel@lists.infradead.org
Subject: Re: [PATCH V2] ARM: dts: bcm283x: Reserve first page for firmware
Date: Tue, 9 May 2017 09:25:54 -0700 [thread overview]
Message-ID: <e2718c25-fdf1-ead1-cbfa-d23bf729a079@gmail.com> (raw)
In-Reply-To: <b6aef857-1454-7931-2c60-6d7b55b7a0a8@raspberrypi.org>
On 05/09/2017 02:04 AM, Phil Elwell wrote:
> The Raspberry Pi startup stub files for multi-core BCM27XX processors
> make the secondary CPUs spin until the corresponding mailbox is
> written. These stubs are loaded at physical address 0x00000xxx (as seen
> by the ARMs), but this page will be reused by the kernel unless it is
> explicitly reserved, causing the waiting cores to execute random code.
>
> Use the /memreserve/ Device Tree directive to mark the first page as
> off-limits to the kernel.
This reserves a 4KB page here, is this good enough, or should we just go
directly to the maximum page granule size possible on an ARM64/Linux
system to be on the safe side?
>
> See: https://github.com/raspberrypi/linux/issues/1989
>
> Signed-off-by: Phil Elwell <phil@raspberrypi.org>
> ---
>
> Changes in V2:
> - Rebase against linux-next
> - Drop downstream-only patch
>
> arch/arm/boot/dts/bcm283x.dtsi | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/boot/dts/bcm283x.dtsi b/arch/arm/boot/dts/bcm283x.dtsi
> index a3106aa..6d12c3e8 100644
> --- a/arch/arm/boot/dts/bcm283x.dtsi
> +++ b/arch/arm/boot/dts/bcm283x.dtsi
> @@ -3,6 +3,8 @@
> #include <dt-bindings/clock/bcm2835-aux.h>
> #include <dt-bindings/gpio/gpio.h>
>
> +/memreserve/ 0x00000000 0x00001000;
Can you put a comment above this /memreserve entry here to remind about
what this is useful for?
Thanks!
> +
> /* This include file covers the common peripherals and configuration between
> * bcm2835 and bcm2836 implementations, leaving the CPU configuration to
> * bcm2835.dtsi and bcm2836.dtsi.
>
--
Florian
next prev parent reply other threads:[~2017-05-09 16:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-09 9:04 [PATCH V2] ARM: dts: bcm283x: Reserve first page for firmware Phil Elwell
2017-05-09 16:25 ` Florian Fainelli [this message]
2017-05-16 22:19 ` Eric Anholt
2017-05-09 16:48 ` Eric Anholt
2017-05-09 16:52 ` Florian Fainelli
2017-05-09 18:10 ` Eric Anholt
2017-05-14 12:50 ` Andreas Färber
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