On 31/05/2021 10:57, Marc Zyngier wrote: > It has been reported that kexec_file doesn't really work on arm64. > It completely ignores any of the existing reservations, which results > in the secondary kernel being loaded where the GICv3 LPI tables live, > or even corrupting the ACPI tables. I'd like to know how the ACPI tables bit happens. ACPI tables should be in EFI_ACPI_RECLAIM_MEMORY or EFI_ACPI_MEMORY_NVS (which isn't treated as usable). EFI's reserve_regions() does this: | if (!is_usable_memory(md)) | memblock_mark_nomap(paddr, size); | | /* keep ACPI reclaim memory intact for kexec etc. */ | if (md->type == EFI_ACPI_RECLAIM_MEMORY) | memblock_reserve(paddr, size); which is called via efi_init(), and all those regions end up listed as reserved in /proc/iomem. (this is why arm64 doesn't call acpi_reserve_initial_tables()) If your firmware puts ACPI tables are in EFI_CONVENTIONAL_MEMORY, you have bigger problems as the kernel could get relocated over the top of them during boot, and even if it doesn't, nothing stops that memory being allocated for user-space. Even acpi_table_upgrade() calls memblock_reserve() and happens early enough not to be a problem. Please share ... enjoyment, optional. (boot with efi=debug and post the EFI memory map and the 'ACPI: FOO 0xphysicaladdress' stuff at the top of the boot log) Thanks, James > Since only crash kernels are imune to this as they use a reserved > memory region, disable the non-crash kernel use case. Further > patches will try and restore the functionality.
