Florian Fainelli <f.fainelli@xxxxxxxxx> writes: > 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@xxxxxxxxxxxxxxx> >> --- >> >> 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! Phil, I chatted with Florian and added in: +/* firmware-provided startup stubs live here, where the secondary CPUs are + * spinning. + */ and tagged and sent a PR for 4.12. Thanks!
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