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Switch the x86 based EFI platform builds to the generic EFI loader, which exposes the initrd via the LoadFile2 protocol instead of the x86-specific setup header. This will launch the Linux kernel via its EFI stub, which performs its own initialization in the EFI boot services context before calling ExitBootServices() and performing the bare metal Linux boot. Given that only Linux kernel versions v5.8 and later support this initrd loading method, the existing x86 loader is retained as a fallback, which will also be used for Linux kernels built without the EFI stub. In this case, GRUB calls ExitBootServices() before entering the Linux kernel, and all EFI related information is provided to the kernel via struct boot_params in the setup header, as before. Note that this means that booting EFI stub kernels older than v5.8 is not supported even when not using an initrd at all. Also, the EFI handover protocol, which has no basis in the UEFI specification, is not implemented. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This is GRUB 2, the second version of the GRand Unified Bootloader. GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more robust, more powerful, and more portable. See the file NEWS for a description of recent changes to GRUB 2. See the file INSTALL for instructions on how to build and install the GRUB 2 data and program files. See the file MAINTAINERS for information about the GRUB maintainers, etc. If you found a security vulnerability in the GRUB please check the SECURITY file to get more information how to properly report this kind of bugs to the maintainers. Please visit the official web page of GRUB 2, for more information. The URL is <http://www.gnu.org/software/grub/grub.html>. More extensive documentation is available in the Info manual, accessible using 'info grub' after building and installing GRUB 2. There are a number of important user-visible differences from the first version of GRUB, now known as GRUB Legacy. For a summary, please see: info grub Introduction 'Changes from GRUB Legacy'