Evangelos Petrongonas 5b86af1ded efi: support booting with kexec handover (KHO)
When KHO (Kexec HandOver) is enabled, it sets up scratch memory regions
early during device tree scanning.  After kexec, the new kernel
exclusively uses this region for memory allocations during boot up to the
initialization of the page allocator

However, when booting with EFI, EFI's reserve_regions() uses
memblock_remove(0, PHYS_ADDR_MAX) to clear all memory regions before
rebuilding them from EFI data.  This destroys KHO scratch regions and
their flags, thus causing a kernel panic, as there are no scratch memory
regions.

Instead of wholesale removal, iterate through memory regions and only
remove non-KHO ones.  This preserves KHO scratch regions, which are good
known memory, while still allowing EFI to rebuild its memory map.

Link: https://lkml.kernel.org/r/b34da9fd50c89644cd4204136cfa6f5533445c56.1755721529.git.epetron@amazon.de
Signed-off-by: Evangelos Petrongonas <epetron@amazon.de>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-09-13 17:32:57 -07:00
2025-09-13 17:32:56 -07:00
2025-09-13 17:32:56 -07:00
2025-08-27 22:45:41 -07:00
2025-02-19 14:53:27 -07:00
2025-08-31 15:33:07 -07:00
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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