# apologies for a bit late updates This patch series is a set of bug fixes to address kexec/kdump failures which are sometimes observed on ACPI-only system and reported in LAK-ML before.
In short, the phenomena are: 1. kexec'ed kernel can fail to boot because some ACPI table is corrupted by a new kernel (or other data) being loaded into System RAM. Currently kexec may possibly allocate space ignoring such "reserved" regions. We will see no messages after "Bye!" 2. crash dump (kdump) kernel can fail to boot and get into panic due to an alignment fault when accessing ACPI tables. This can happen because those tables are not always properly aligned while they are mapped non-cacheable (ioremap'ed) as they are not recognized as part of System RAM under the current implementation. After discussing several possibilities to address those issues, the agreed approach, in my understanding, is * to add resource entries for every "reserved", i.e. memblock_reserve(), regions to /proc/iomem. (NOMAP regions, also marked as "reserved," remains at top-level for backward compatibility.) * For case (1), user space (kexec-tools) should rule out such regions in searching for free space for loaded data. * For case (2), the kernel should access ACPI tables by mapping them with appropriate memory attributes described in UEFI memory map. (This means that it doesn't require any changes in /proc/iomem, and hence user space.) Please find past discussions about /proc/iomem in [1]. Patch#1 addresses kexec case, for which you are also required to update user space. See necessary patches in [2]. If you want to review Patch#1, please also take a look at and review [2]. Patch#2 and #3 addresses kdump case. This is a revised version after Ard's comments.[3] [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-March/565980.html [2] https://git.linaro.org/people/takahiro.akashi/kexec-tools.git arm64/resv_mem [3] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-April/573655.html AKASHI Takahiro (2): arm64: acpi,efi: fix alignment fault in accessing ACPI tables at kdump init: map UEFI memory map early if on arm or arm64 James Morse (1): arm64: export memblock_reserve()d regions via /proc/iomem arch/arm64/include/asm/acpi.h | 23 ++++++++++++------ arch/arm64/kernel/acpi.c | 11 +++------ arch/arm64/kernel/setup.c | 38 ++++++++++++++++++++++++++++++ drivers/firmware/efi/arm-runtime.c | 27 ++++++++++----------- init/main.c | 3 +++ 5 files changed, 72 insertions(+), 30 deletions(-) -- 2.17.0 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
