Re: [PATCHv5 06/12] x86/boot/compressed: Handle unaccepted memory

From: Wander Lairson Costa
Date: Fri Apr 29 2022 - 09:11:18 EST

On Mon, Apr 25, 2022 at 06:39:28AM +0300, Kirill A. Shutemov wrote:
> The firmware will pre-accept the memory used to run the stub. But, the
> stub is responsible for accepting the memory into which it decompresses
> the main kernel. Accept memory just before decompression starts.
> The stub is also responsible for choosing a physical address in which to
> place the decompressed kernel image. The KASLR mechanism will randomize
> this physical address. Since the unaccepted memory region is relatively
> small, KASLR would be quite ineffective if it only used the pre-accepted
> area (EFI_CONVENTIONAL_MEMORY). Ensure that KASLR randomizes among the
> entire physical address space by also including EFI_UNACCEPTED_MEMOR