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The following procedure to build xen/pvgrub is broken. git clone https://git.savannah.gnu.org/git/grub.git cd grub ./bootstrap mkdir build-xen cd build-xen ../configure --with-platform=xen make It fails with the message: /usr/lib64/gcc/x86_64-suse-linux/10/../../../../x86_64-suse-linux/bin/ld: section .note.gnu.property VMA [0000000000400158,0000000000400187] overlaps section .bss VMA [000000000000f000,000000000041e1af] The most significant factor is that new assembler (GNU as) generates the .note.gnu.property section as default. This note section overlaps with .bss because it doesn't reposition with -Wl,-Ttext,0 with which the base address of .text section is set, rather the address of .note.gnu.property is calculated for some reason from 0x400000 where the ELF executable defaults to start. Using -Ttext-segment doesn't help either, though it is said to set the address of the first byte of the text segment according to "man ld". What it actually does is to override the default 0x400000, aka the image base address, to something else. The entire process can be observed in the default linker script used by gcc [1]. Therefore we can't expect it to achieve the same thing as -Ttext given that the first segment where .text resides is offset by SIZEOF_HEADERS plus some sections may be preceding it within the first segment. The end result is .text always has to start with non-zero address with -Wl,-Ttext-segment,0 if using default linker script. It is also worth mentioning that binutils upstream apparently doesn't seem to consider this as a bug [2] and proposed to use -Wl,-Ttext-segment,0 which is not fruitful as what has been tested by Gentoo [3]. As long as GRUB didn't use ISA information encoded in .note.gnu.property, we can safely drop it via -Wa,-mx86-used-note=no assembler option to fix the linker error above. This is considered a better approach than using custom linker script to drop the .note.gnu.property section because object file manipulation can also be hampered one way or the other in that linker script may not be helpful. See also this commit removing the section in the process of objcopy. 6643507ce build: Fix GRUB i386-pc build with Ubuntu gcc [1] In /usr/lib64/ldscripts/elf_x86_64.x or use 'gcc -Wl,--verbose ...' PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x400000)); . = SEGMENT_START("text-segment", 0x400000) + SIZEOF_HEADERS; [2] https://sourceware.org/bugzilla/show_bug.cgi?id=27377 [3] https://bugs.gentoo.org/787221 Signed-off-by: Michael Chang <mchang@suse.com> 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'