From: Matt Fleming Date: Fri, 11 Jul 2014 07:45:25 +0000 (+0100) Subject: x86/efi: Enforce CONFIG_RELOCATABLE for EFI boot stub X-Git-Tag: v3.17-rc1~36^2^2 X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=7b2a583afb4ab894f78bc0f8bd136e96b6499a7e;p=cascardo%2Flinux.git x86/efi: Enforce CONFIG_RELOCATABLE for EFI boot stub Without CONFIG_RELOCATABLE the early boot code will decompress the kernel to LOAD_PHYSICAL_ADDR. While this may have been fine in the BIOS days, that isn't going to fly with UEFI since parts of the firmware code/data may be located at LOAD_PHYSICAL_ADDR. Straying outside of the bounds of the regions we've explicitly requested from the firmware will cause all sorts of trouble. Bruno reports that his machine resets while trying to decompress the kernel image. We already go to great pains to ensure the kernel is loaded into a suitably aligned buffer, it's just that the address isn't necessarily LOAD_PHYSICAL_ADDR, because we can't guarantee that address isn't in-use by the firmware. Explicitly enforce CONFIG_RELOCATABLE for the EFI boot stub, so that we can load the kernel at any address with the correct alignment. Reported-by: Bruno Prémont Tested-by: Bruno Prémont Cc: H. Peter Anvin Cc: Signed-off-by: Matt Fleming --- diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index fcefdda5136d..a24097768463 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1536,6 +1536,7 @@ config EFI config EFI_STUB bool "EFI stub support" depends on EFI + select RELOCATABLE ---help--- This kernel feature allows a bzImage to be loaded directly by EFI firmware without the use of a bootloader.