[RFC v1 0/4] arm64: MMU enabled kexec kernel relocation

Pavel Tatashin pasha.tatashin at soleen.com
Tue Jul 16 09:56:37 PDT 2019

Added identity mapped page table, and keep MMU enabled while
kernel is being relocated from sparse pages to the final
destination during kexec.

More description about the problem I am trying to solve here, can be
found here:

This patch series works in terms, that I can kexec-reboot both in QEMU
and on a physical machine. However, I do not see performance improvement
during relocation. The performance is just as slow as before with disabled

Am I missing something? Perhaps, there is some flag that I should also
enable in page table? Please provide me with any suggestions.

Pavel Tatashin (4):
  arm64, mm: identity mapped page table
  arm64, kexec: interface preparation for mmu enabled kexec
  arm64, kexec: add kexec's own identity page table
  arm64: Keep MMU on while kernel is being relocated

 arch/arm64/include/asm/ident_map.h  |  26 ++++++
 arch/arm64/include/asm/kexec.h      |   5 +-
 arch/arm64/kernel/cpu-reset.S       |   8 --
 arch/arm64/kernel/cpu-reset.h       |   7 +-
 arch/arm64/kernel/machine_kexec.c   | 128 +++++++++++++++++++++-------
 arch/arm64/kernel/relocate_kernel.S |  36 +++++---
 arch/arm64/mm/Makefile              |   1 +
 arch/arm64/mm/ident_map.c           |  99 +++++++++++++++++++++
 8 files changed, 255 insertions(+), 55 deletions(-)
 create mode 100644 arch/arm64/include/asm/ident_map.h
 create mode 100644 arch/arm64/mm/ident_map.c


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