Sam Edwards cef313931d arm64: dts: broadcom: bcmbca: bcm4908: Reserve CFE stub area
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@gmail.com>
Link: https://lore.kernel.org/r/20241005050155.61103-2-CFSworks@gmail.com
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
2024-12-17 11:39:20 -08:00
2024-09-01 20:43:24 -07:00
2022-09-28 09:02:20 +02:00
2024-12-01 14:28:56 -08:00
2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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