It recently became apparent that using kexec with kexec_file_load() on arm64 is pretty similar to playing Russian roulette. Depending on the amount of memory, the HW supported and the firmware interface used, your secondary kernel may overwrite critical memory regions without which the secondary kernel cannot boot (the GICv3 LPI tables being a prime example of such reserved regions). It turns out that there is at least two ways for reserved memory regions to be described to kexec: /proc/iomem for the userspace implementation, and memblock.reserved for kexec_file. And of course, our LPI tables are only reserved using the resource tree, leading to the aforementioned stamping. Similar things could happen with ACPI tables as well. On my 24xA53 system artificially limited to 256MB of RAM (yes, it boots with that little memory), trying to kexec a secondary kernel failed every times. I can only presume that this was mostly tested using kdump, which preserves the entire kernel memory range. This small series aims at triggering a discussion on what are the expectations for kexec_file, and whether we should unify the two reservation mechanisms. And in the meantime, it gets things going... Marc Zyngier (2): firmware/efi: Tell memblock about EFI reservations ACPI: arm64: Reserve the ACPI tables in memblock arch/arm64/kernel/acpi.c | 1 + drivers/firmware/efi/efi.c | 23 ++++++++++++++++++++++- 2 files changed, 23 insertions(+), 1 deletion(-) -- 2.29.2 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
